Pesticides constitute the major source of potential environmental hazard to man and animal as they are present and concentrated in the food chain. This study was conducted on 136 samples of water, sediment and fish for detection and determination of pesticide residues in this ecosystem. Highly significant differences were found in levels of Indian, heptachlor, endrin, dieldrin, P,P'-DDE and propoxur in River Nile water when compared with that of Manzala Lake. Levels of Indian, endrin, malathion and diazinon were significantly higher in soil sediment of Manzala Lake, while the levels of heptachlor, aldrine, P,P'-DDE, DDT, parathion, propoxur and zectran were significantly higher in soil sediment of River Nile. Boury fish of Manzala Lake contained higher levels of heptachlor, aldrin, P,P'-DDE and malathion, while boury fish of River Nile contained a higher level of zectran only. This survey, thus indicated that Manzala Lake and even the River Nile which was used as control are heavily contaminated with chlorinated hydrocarbons (Indian, heptachlor, aldrin, endrin, dieldrin, P,P'-DDE and DDT), organic phosphorus compounds (malathion, dimethoat, diazinon and parathion) and carbamate pesticides (propoxur and zectran).