In this study, the effect of salt concentration on growth characteristics and pigment accumulation of two strains of Dunaliella viridis Teodoresco (Ayvalik and Dalyan) which were cultured both at the laboratory and outdoor conditions were studied. The highest growth was found at 2M NaCl (1.33 +/- 0.12 d(-1)) for outdoor conditions. The highest cell numbers were observed at Ayvalik strain for both laboratory (8.06 +/- 0.40 x 10(6) cell ml(-1)) and outdoor conditions (5.83 +/- 0.19 x 10(6) cell ml(-1)). The minimum cell numbers determined at 3M NaCl cultures for laboratory experiments while it was found at 1M NaCl for outdoor cultures. It was measured that the cell volume of laboratory cultures (67.6 +/- 14.4 - 198.7 +/- 9.8 mu m(3)) were higher than outdoor cultures (48.7 +/- 9.7 - 110.5 +/- 4.9 mu m(3)). The total chlorophyll (a+b) and carotenoid contents were the highest at laboratory cultures for all salinity concentrations (p<0.05). The total chlorophyll and carotenoid concentration increased with salinity increase at outdoor conditions. In this study, growth rates, cell density and pigment content of two strains of D. viridis (Ayvalik and Dalyan) was determined and compared both under controlled laboratory and outdoor conditions with different salinity regimes. The results showed that the growth parameters and the pigment composition of D. viridis Ayvalik and Dalyan strains were strongly dependent on salinity.