This study was conducted in Seyhan River between May 1997 and May 1998. Basic haematological parameters and effects of seasonal differences on these parameters were determined in Roach (Rutilus rutilus, Linnaeus, 1758) and Spotted Barb (Capoeta barroisi, Lortet, 1894) species which had adapted to water polluted by agricultural, industrial and domestic wastes. The waste of slaughterhouses also flowed into the region. The results of the study showed that there were deviations from standard values for most of the haematological parameters for R. rutilus indicating that R. rutilus individuals were affected by environmental stress factors more than those of C. barroisi.