Summary:-Non domestic birds are useful as bioindicators of environmental pollution because they are often at the top of food chain, ubiquitous, and many are abundant and common, making collecting possible. These birds have the advantage of being large, wiThis study was carried on cattle egrets which were collected from sharkia province to determine the level of pesticide residues in their tissues and eggs.I- The organochlorine residues in tissues and eggs of cattle egrets:2. livers : Analysis of organochlorine residues in liver samples revealed that the mean concentrations of α-HCH, β-HCH, p,p’-DDE, dieldrin and endrin were 111.78, 33.99, 53.64, 63.71 and 2. Abdominal fats: The abdominal fat samples from investigated cattle egrets had α-HCH, β-HCH, o,p’-DDT, p,p’-DDE, endrin and heptachlor epoxide residues with amean values of 11.16, 74.55, 7.22, 8.69, 696.03 and 102.35 ng/g wet weight, respectively. While Monognetic trematode (Gyrodactylus sp.) was isolated with prevalence of 25% and showed the highest infestation during summer (80%) and the lowest in winter (20%). Dignetic trematodes (Oreintochridum batrachoidus) were isolated with prevalence of 40% and showed the highest infestation during spring (67%) followed by summer (41%), autumn (35%) and the lowest in winter (17%). Cestodes (Monobothrium chalmersius) were isolated with prevalence of 32% and showed the highest infestation during winter (46%) followed by autumn (38%), spring (27%) and the lowest one in summer (17%). Nematodes (Procamallanus laviconchus) were also isolated with prevalence of 33% and showed the highest infestation during summer followed by spring (42%), autumn (20%) and the lowest one occurred during winter (12%).