The objective of this study is to evaluate the bacterial count and heavy metal concentration of river water on fish micronuclei. Fish and water samples are carried out in 1 May to 1 June 2013 from Tigris River. A total of fifty three fish sample are studied. The bacteriological quality of water showed that the total viable count is ranged from 150×103 to 352×103 cfu/ml and fecal coliform counts was 1250 cell/100ml during the study period. All the metals (Cu, Hg, Pb, and Zn) are within the normal limit, but Cd was slightly elevated in river water samples. The appearance of micronuclei in red blood cells of all fish species is detect , by recording a larger number of it, in ( Abu Alsomere , Hishne , Bannini Kaber al fam & Karkoor ahmar) species compared with (Abu AL hakam , Nabbash , Kattan , Himri & Tela shami ) species. There is a difference in the percentages of the leukocytes types in different fish species, the highest percentage (12.3) of lymphocyte is recorded in Barbus xanthopterus and the lowest (1.5) is in Garra rufa
