When three Thraustochytrium stains were cultivated in liquid media containing 2.5% starch and 0.2% yeast extract, initial pH 6.0, with shaking under fluorescent light for five days at 25 degrees C, similar biomass yields were observed (9.7-10.3 g L-1). Contents of docosahexaenoic acid (DHA) in biomass varied: 0.15, 3.55 and 6.40% w/w for T. striatum ATCC 24473. T. aureum ATCC 34304 and T. roseum ATCC 28210, respectively. In further studies, T. roseum produced a maximum titer of 0.85 g of DHA per liter of culture broth. The DHA content of total lipids ranged from 46-49% w/w.