OceanaGold : Provides Annual Resource and Reserve Statement Update

MEDIA RELEASE

28 March 2019

OCEANAGOLD PROVIDES ANNUAL RESOURCE AND RESERVE STATEMENT

UPDATE

(MELBOURNE) OceanaGold Corporation (TSX: OGC) (ASX: OGC) (the "Company") is pleased to provide its updated annual Resource and Reserve ("R&R") statement for the year ended December 31, 2018.

Highlights

•Total Proven and Probable Mineral Reserves of 5.56 Moz1 of gold, 3.38 Moz of silver and 0.14 Mt of copper, with growth in gold reserves offsetting approximately 50% of 2018 mining depletion

•Total Measured and Indicated Mineral Resources of 8.59 Moz of gold, 5.52 Moz of silver and 0.16 Mt of copper, with gold resource growth nearly offsetting 2018 mining depletion

•Total Inferred Mineral Resources of 3.6 Moz of gold, 3.5 Moz of silver and 0.03 Mt of copper. A 42% year on year increase, net of mining depletion.

•Martha Underground Indicated Mineral Resource increased to 0.33 Moz of gold and 1.30 Moz of silver while Inferred Mineral Resources increased to 0.67 Moz of gold and 2.47 Moz of silver.

•Initial WKP resource including 0.23 Moz of gold in Indicated Mineral Resources and 0.4 Moz of gold in Inferred Mineral Resources.

Mick Wilkes, President and CEO, "OceanaGold has a significant mineral endowment that has grown over the past several years. Exploration is a key component of our value creating strategy and we have increased our exploration budget each year since 2015. Operating and exploring in prolific gold districts in the United States, New Zealand and the Philippines has afforded us the opportunity to make prudent investments in extensive drill programs that have translated into growth of our resource base"

"For the past few years, we have described our confidence in significantly increasing the resource base and mine life of our New Zealand operations. Over the course of the past 12 months, we have done just that with significant increases at the Martha Underground and initial resource at our newest discovery at WKP. We have also achieved exploration success at Macraes where we are currently investigating a mine life increase through resource conversion and recent discovery of higher grade ore at depth at Golden Point."

"At Haile, we continue to achieve positive exploration results by identifying new pockets of mineralisation within the existing operating footprint and at depth. We do look forward to further extensive drilling at deeper

1Moz = million troy ounces.

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targets once the Horseshoe underground is built. At Didipio, drilling towards the base of Panel 2 of the underground has yielded increases to the resource at the operation."

Table 1: Updated Mineral Reserves (as at December 31, 2018)

PROJECT			PROVEN				PROBABLE					PROVEN & PROBABLE
AREA	Cut-Off	Mt	Au g/t Ag g/t Cu %			Mt	Au g/t Ag g/t Cu %			Mt	Au g/t Ag g/t Cu % Au Moz Ag Moz					Cu Mt
MACRAES Open Pit	0.4 g/t Au	10.8	1.11	.	.	22.2	0.94	.	.	33.0	0.99	.	.	1.05	.	.
MACRAES Underground	1.2 g/t Au	0.5	2.74	.	.	0.97	2.06	.	.	1.47	2.29	.	.	0.11	.	.
BLACKWATER
WAIHI Open Pit	0.5 g/t Au	0.2	3.05	30.46 .		0.7	2.91	29.11 .		0.8	2.94	29.37 .		0.08	0.77	.
WAIHI Underground	2.9 g/t Au	0.3	5.63	11.25 .		0.3	4.88	9.76	.	0.6	5.31	10.61 .		0.10	0.20	.
NEW ZEALAND		11.8	1.33			24.1	1.08			35.9	1.16			1.34	0.97	.
DIDIPIO Open Pit	0.4 g/t AuEq	19.4	0.39	2.08	0.33	.	.	.	.	19.4	0.39	2.08	0.33	0.24	1.29	0.06
DIDIPIO Underground	1.3 g/t AuEq	9.9	2.09	2.19	0.50	7.3	1.23	1.79	0.40	17.2	1.73	2.02	0.46	0.95	1.12	0.08
PHILIPPINES		29.2	0.97			7.3	1.23			36.6	1.02			1.20	2.41	0.14
HAILE Open Pit	0.45 g/t Au	10.2	1.86	.	.	41.1	1.50	.	.	51.3	1.57	.	.	2.59	.	.
Haile Underground	1.5 g/t Au	.	.	.	.	3.1	4.38	.	.	3.1	4.38	.	.	0.44	.	.
USA		10.2	1.86			44.2	1.70			54.4	1.73			3.03	.	.
TOTAL		51.3	1.23			75.5	1.46			127	1.36			5.56	3.38	0.14

Notes:

1.Mineral Reserves are reported within current mine designs based upon US$1,300/oz gold, US$3.25/lb copper and US$17/oz silver.

2.Reported estimates of contained metal do not make allowances for processing losses.

Figure 1: Changes to Proven & Probable Mineral Reserves

The Company's Proven and Probable ("P&P") Reserves stand at 5.56 Moz of gold, 3.38 Moz of silver and 0.14 Mt of copper. Year-on-year, growth in reserves has offset 36% of 2018 mining depletion.

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Table 2: Updated Mineral Resources - Measured and Indicated (as at December 31, 2018)

Figure 2: Changes to Measured & Indicated Mineral Resources

All reported Measured and Indicated Resources include Mineral Reserves.

On a consolidated basis, the Company has offset 2018 mining depletion with resource growth, mainly at Waihi, resulting in Measured and Indicated ("M&I") Resources totalling 8.59 Moz of gold, 5.52 Moz of silver and 0.16 Mt of copper, a small year-on-year decrease of 0.09 Moz Au, due to 2018 mining depletion largely being offset by the addition of the new Martha and WKP underground resources.

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Table 3: Updated Mineral Resources - Inferred Resource Statement (as at December 31, 2018)

Notes for Measured, Indicated and Inferred Resources:

1.Mineral Resources include Mineral Reserves.

2.Macraes open pit resources constrained by a NZ$2,083/oz gold price pit shell.

3.Haile open pit resources constrained by a US$1,500/oz gold price pit shell.

4.Waihi open pit resources are reported within a pit design to the 890mRL.

5.WKP and MUG resources were publicly released on March 7, 2019 and February 22, 2019 respectively, but are based on drilling and geological information compiled in 2018.

6.50% of Waihi Measured & Indicated Resources are from Martha Underground reported at a 2.15 g/t Au cut-off, 35% from WKP reported at a 3.0 g/t Au cut-off and 15% from Correnso reported at a 2.9 g/t Au cut-off

7.62% of Waihi Inferred Resources are from Martha Underground which are reported at a 2.15 g/t Au-cut-off & 39% from WKP reported at a 3.0 g/t Au cut-off

8.For Didipio, all in-situ open pit resources have been depleted. Only stockpiles remain. Underground resources reported between the 2,460mRL and 1,980mRL with gold equivalence (AuEq) cut-off based on US$1,500/oz gold and US$3.50/lb copper.

Figure 3: Changes to Inferred Resources

Consolidated Inferred Resources increased to 3.6 Moz of gold, 3.5 Moz of silver and 0.03 Mt of copper. This represents a 42% year on year increase in Inferred gold resources mainly due to growth at Waihi.

Table 4 - Updated Mineral Resources - Minority Interest in Assets (as at December 31, 2018)

PROJECT		MEASURED			INDICATED			INFERRED
AREA	Mt	Au g/t	Moz	Mt	Au g/t	Moz	Mt	Au g/t	Au Moz
SAMS CREEK	.	.	.	2.0	1.77	0.11	2.0	1.3	0.1
TOTAL	.	.	.	2.0	1.77	0.11	2.0	1.3	0.1

Notes:

1. OceanaGold has a 20% interest in the Sam's Creek Project. Reported at a 0.7 g/t Au cut-off and factored by the percentage ownership.

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New Zealand

Waihi

Figure 4: Changes to Waihi Proven & Probable Mineral Reserves

Combined open pit and underground P&P Reserve at Waihi as at 31st December 2018 stood at 0.18 Moz after mine depletion. The Company continues to advance the Martha Underground Project having received the resource consents (permits) to proceed to operations. The Company is in the process of implementing the project through mine designs, construction and additional drilling which will add considerably to the reserves in 2019.

Figure 5: Changes to Waihi Measured & Indicated Mineral Resources

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