The present study was carried on the Wadi El - Rayan lakes from spring 2015 to winter 2016.  Seasonal water samples were collected from several selected sites to cover most parts of the two lakes to assess some heavy metals concentration (Fe, Pb, Cu, Cd, Zn and Mn). Samples of Tilapia Spp. fish were collected regularly during four successive seasons from Wadi El-Rayan Lakes (upper) and (lower). To evaluate the concentration of different heavy metals in the tissues (muscles, liver, gills). Also Biochemical parameters in fish serum such as analysis of (Glucose, Urea, Creatinine, the activity of liver enzymes (AST - ALT) enzyme activity, Triglycerides, Total Cholesterol, and Total proteins were analyzed. The results showed that the level of heavy metals (Fe, Pb, Cu, Cd, Zn and Mn) in the permissible limit except (Fe and Pb) were higher than the permissible limit and it concentration in water samples follow the order Fe > Mn> Pb> Cu> Zn and Cd also, the results showed the concentration in fish (muscles) within the permissible limits except (Fe). The results of biochemical parameters showed an increase in these parameters (serum Glucose, Urea, Creatinine, Cholesterol, Triglycerides, Total proteins, AST and ALT), this increase was significant in (Glucose, Urea, Creatinine, Cholesterol, Triglycerides, AST and ALT activities) and not significant in (Total proteins).