In order to get the high liquefaction yield from marine algae cell mass to fuel oil, the effect of salt stress on the accumulation of lipids and triacylglyceride in Dunaliella cells was investigated. Although initial NaCl concentration higher than 1.5 M markedly inhibited cell growth, increase of initial NaCl concentration from 0.5 (equal to sea water) to 1.0 M resulted in a higher intracellular lipid content (67%) in comparison with 60% for the salt concentration of 0.5 M. Addition of 0.5 or 1.0 M NaCl at mid-log phase or the end of log phase during cultivation with initial NaCl concentration of 1.0 M further increased the lipid content (70%).