Ammi majus (A.majus ) fruit extract in concen-tration of 166 ppm and 234 ppm as LC50 and LC99,99 was previously succeed as effective mol-luscicide against schistosoma snails . The present study aimed at testing the effect of this mollusci-cide doses on some physiological functions of the Nile tilapia (Oreochromis niloticus=O. niloticus) to show whether this extract is safe and non toxic for these fishes or not . O. niloticus were brought from Bahr Muess at Zagazig City and reared in the laboratory had no clinical signs or abnormal  changes externally and in the internal organs of the fish after ex ici posture to the two molluscicidal-Oncentrati“ntrations for 24, 48 and 72 h . The biochemical , indicated that the levels of: glu-OSE, total protei in, uric acid, urea, aminotransfe-Tases (aspartate aminotransferase=AST and alanine aminotransferase = ALT), electrolytes (Na+, K+, Ca++ and P++) and hormones (Triiod-othyronine =T3, Tetraiodothyronine =thyroxine =T4 and cortisol) in the serum of the exposed Nile tilapia show no significant alterations after the three exposure times in comparing with con-trols the non exposed fishes . The study conclud-ed that A. majus fruit extract at their molluscici-dal doses has no hazard effect on O. niloticus at the condition of the present study . Further studywill be don on different types of the Nile fishes of different ages before commercial application of the new molluscicide .