Biochemical analysis, hacmatological properties and carcass composition of Oreochromis niloticus were studied in relation to different levels of sew-age watcr pollution for a period of 91 days. The fish were stocked in glass aquaria (150 liters each) and fed on artificial diet (28% protein). Itwas noticed that, the dissolved oxygen and totalalkalinity of the water were decreased with the in-creasing of sewage pollution level. While ammo-nia, nitrate, phosphate, silicate and pH value were slightly increased. The liver biochemical constituents, blood parame-ters, scrum compositions and proximate analysis of rearing fish were increased from control group (100% freshwater) to the first level of sewage pollution (75% fresh water and 25% pollutant water).‘While above this level, the previous values were gradually decreased. On the other hand, the val-Piducs of hcpatosomatic index and scrum glucosc were increased with the increasing of sewage pol-lution concentration.