Description: This study was conducted with the purpose to assess the condition of some vital organs (heart, spleen, kidney and gonads) of Pelophylax ridibundus populations that live in conditions of anthropogenic pollution in biotopes in southern Bulgaria, through analysing their relative weights: cardiosomatic index (CSI), spleenosomatic index (SSI), renosomatic index (RSI) and gonadosomatic index (GSI). Populations from three biotopes were investigated: a relatively clean biotope (the control) and two polluted biotopes (with domestic sewage pollution and heavy metal pollution). We found that in both sexes, in conditions of pollution, the relative weight of the heart, spleen and kidney increased. In the population from biotope with heavy metal pollution, the relative weight of gonads was bigger