Abstract: Four strains of Dunaliella salina (I, G1, A and MUR8) were cultivated under the three salinity regimes (1, 2 and 3 M NaCl) to examine the effect of salinity on the ß-carotene synthesis per cell and to compare the ß-carotene production per culture volume and the rate of growth. During the 30 days of the experiments the batch cultures maintained in the 300 flasks containing 100 of Johnson`s medium under the low irradiance (100 μmol photon m-2 s-1) with a 12/8 h light/dark regime and a continuous shaking. The results showed that the inductive effect of salinity on ß-carotene accumulation per cell was strain dependent and when the values for the strains IR-1 and Gh-U were slightly higher at 3 M NaCl compare to lower salinities, there were no direct relationships between the concentrations of salt and the ß-carotene contents per cell in other two strains (MUR-8 and Au-W). On the other hand, increase the salinity result in serious decreasing in the cell number and the ß-carotene content per culture volume of all strains during the experiment. The highest ß-carotene content per (14.2 mg L-1) was obtained at 1 M NaCl in the suspension culture of the strain Au-W.