The Pripyat Trough and the Caspian Depression are examples of basins with chloride and sulfate type evaporite formations, respectively. Patterns of sulfur isotope distribution in these basins are essentially different. Sulfur isotopic composition of sulfate minerals in the Caspian Depression becomes lighter from the gypsum stage d 34 S 113:9 ^0:3½ toward the chloride stage (112.7 ^0.2½). An opposite isotopic trend occurs in the Pripyat Trough: d 34 S are, respectively, 122.8 ^1.0 and 25.3 ^0.5½. Pyrite formed in the chloride stage in the Caspian Depression is signi®cantly depleted in 34 S with respect to the initial sulfate of the basin d 34 Ssulfate-py 22:5 ^2:1½: Dd 34 S(sulfate-py) in the Pripyat Trough is lower (17.6 ^1.2½). Diagenetic anhydrites from the intersaliferous and subsaliferous formations are enriched in 34 S relative to the sulfur isotope values measured from the anhydrites in the main salts. This enrichment is higher in the Pripyat Trough (average Dd 34 S 2.7±5.2½) than in the Caspian Depression (0.9±2.1½). The above differences are well explained in the terms of chemical systems that are limited or unlimited with respect to sulfur during the sulfate reduction process. Brines act as sulfur limited systems in chloride type basins and as sulfur unlimited systems in sulfate type ones.