This study investigated the influence of anthropogenic salinization on planktonic rotifer communities and traced changes in their diversity along a salinity gradient. The experiment was conducted in 14 ponds of varied anthropogenic origin located in Poland’s Silesian Upland. On the basis of the mean concentration of total dissolved solids (TDS) and principal component analysis (PCA), the water bodies were divided into 4 groups in respect to salinity: freshwater ponds, TDS < 500 mg·dm^-3; subsaline ponds, TDS = 500-3,000 mg·dm^-3; hyposaline ponds, TDS = 3,000-20,000 mg·dm^-3; and mesosaline ponds, TDS = 20,000-50,000 mg·dm^-3. An increase in salinity resulted in a decrease of rotifer species richness and diversity. Salinity also had a negative effect on mean rotifer density. The highest densities were recorded in freshwater and hyposaline ponds, whereas the lowest were in subsaline and mesosaline waters. Rotifer species richness differed significantly at 2 salinity thresholds: TDS = 500 mg·dm^-3 and 20,000 mg·dm^-3.