Sarcoplasmic proteinograms of both sexes of Oreochromis niloticts and O.aureus from Manzalla lake, River Nile (13enha area) and private fish farm (Sharkia province) were fractionated using 7.5% polyacrylamide gel electrophoresis. Polymorphism, relative mobility and similarity coefficient (SC) between mobilities of fractions were studied. Three fractions (#9, 10 and 13) absolutely appeared :n all individuals. Thirteen fractions with different degrees of polymorphism were detected for both species. Different relative mobility values were recorded and significant sex variations were shown in the fraction #1 of O.niloticus from the river Nile and Fraction #4 of aaureus from Manzalla lake. Highest similarity coefficients were calculated in both sexes of O.niloticus from Manzalla lake and that from the river Nile. SC values were lower in specimens from fish farms than those from either Manzalla lake or river Nile. This indicated that, the relative genetic purity (from the biochemical point of view) was higher for O.niloticus from the river Nile, followed by that from Manzalla, while, that from the private fish farm had the lowest one. When comparing the two species of the same locality, very highly SC were detected in both sexes from Manzalia lake, while, less SC were observed in the private fish farm.