The major gold miner said Porgera was impacted by lower underground and open pit production, along with power outages and unplanned maintenance which affected mill throughput.
In the March quarter the mine produced about 130,000oz, but that result was also lower than previously anticipated due to heavy rainfall and "pit wall remediation activities".
Barrick's wider Australia Pacific business unit produced about 460,000 ounces at total cash costs of $US611/oz in the June quarter.
This unit is forecast to produce 1.8-2 million ounces for this calendar year at total cash costs of $610-635/oz.
Barrick owns 95% of the Porgera mine in Enga province.