The effect of the composition of artificial sea water (ASW) medium on the growth properties and docosahexaenoic acid (DHA) production from Thraustochytrium aureum ATCC 34304 was investigated. A maximum dry cell weight (DCW) of 3.71 g/l was obtained when the NaCl and MgSO4 concentration in the ASW media were 15 and 0 g/l, respectively. The maximum initial specific growth (ISG) rate of 0.16 was attained at 7.5 g/l NaCl and 18 g/l MgSO4, while the minimum ISG rate (0.02) was obtained at 5.0 g/l NaCl and 4.5 g/l MgSO4. The least doubling time required for biomass production was 4.3 h at 7.5 g/l NaCl and different MgSO4 concentrations. A maximum of 7.9 g/l DCW was obtained on the fourth day of cultivation at 30 g/l glucose and 2.5 g/l (each) yeast extract (YE) and peptone. The DHA content in the lipids was significantly affected by the concentration of glucose and nitrogen sources (YE and peptone) in the ASW medium. At the lowest glucose (10 g/l) and YE/peptone (0.5 g/l) concentration and highest glucose (30 g/l) and YE/peptone (2.5 g/l) concentration, the DHA content was 34.725 and 40.33%, respectively, relative to total lipid content. However, the DHA content in the lipid was not affected by the NaCl and MgSO4 concentration. At the lowest NaCl (2.5 g/l) and MgSO4 (4.5 g/l) concentration and highest NaCl (60 g/l) and MgSO4 (18 g/l) concentration the DHA content was 39.62 and 38.48%, respectively. The maximum DHA content in the lipid was 49.01% after four days of cultivation when 7.5 g/l NaCl and 4.5 g/l MgSO4 were in the ASW medium. The growth properties of T.aureum ATCC 34304 for biomass production and DHA yield in the lipid content were found to be affected by NaCl and glucose concentration.