This study attempted to characterize the effects of NaCl and MgSO4 as the primary components of sea salt affecting the yields of production of polyunsaturated fatty acids (PUFAs) by Thraustochytrium aureum ATCC 34304. Reductions in the NaCl concentration of the culture medium suppressed the formation of palmitic acid (PA, C16 : 0) but enhanced the production of PUFAs, which induced an increase of the concentration of docosahexaenoic acid (DHA, C22 : 6) up to 46.65% from 44.26%. MgSO4 revealed a similar, yet more highly significant, effect on the fatty acids profile than NaCl. The yields of PUFAs and DHA showed maximum values such as 67.10% and 49.47%, respectively, at the concentration of 10 g L.1 for NaCl and 0 g L.1 for MgSO4. However, the quantities of mono- and diunsaturated fatty acids, oleic acid (OA, C18 : 1) and linoleic acid (LA, C18 : 2) at the same concentrations, were compared with those of normal culture medium. Additionally, it was investigated that the increase of culture temperature reduced PUFAs contents but the reductions were recovered by the removal of MgSO4 form the culture medium, which showed that concentration of salts and culture temperature affected independently the production of PUFAs in T. aureum.