gamma-Linolenic acid (GLA) production using a high GLA producing marine green alga, Chlorella sp. NKG 042401, was studied. GLA was presented in the galactolipid fraction (37.9%/total fatty acids). The effects of growth conditions on GLA production were studied. Optimum salinity for GLA production was 5 g l-1, at which salinity the highest cell concentration was achieved, resulting in a 1.6-fold increase in GLA productivity. Total fatty acid, however, was not drastically affected by change of salinity. Nitrogen starvation decreased the ratio of unsaturated fatty acids, and consequently GLA ratio in total fatty acid decreased. The urea adduct method was used to concentrate GLA from crude extract. As a result, after 5 sequential concentration procedures, GLA was concentrated 5-fold with a yield of 49%.