The export of oil products also fell, by 10.7% year-on-year to 8.6 million metric tons.
The decreases were due to redirecting oil to the domestic market.
Gazprom Neft produced 30.78 million tons (226.2 million barrels) of oil in 2008, down 5.8% against 2007.
Alexander Dyukov, Gazprom Neft's board chairman, said the company increased oil refining 8.7% year-on-year to 28.5 million metric tons in 2008.
"The company has managed to substantially increase oil refining from 24.5 million metric tons to 28.5 million metric tons in the past two years. We are set to increase oil refining further in the next few years. We plan to increase oil refining by another 4-5 million metric tons annually, mostly owing to our capacities at the Moscow oil refinery and in Yaroslavl," he said when signing a cooperation agreement with the government of the Leningrad Region.
Gazprom Neft, known as Sibneft before it was taken over by Gazprom in September 2005, produced 32.7 million metric tons (240 million barrels) of crude in 2007, posting a U.S. GAAP net income of $4.14 billion.