Astudy was conducted to determine the effect of vitamin E, (a-tocopherol acetate a-TOH) supplementation on the fecundity and reproductive performance of Nile tilapia Oreochromis niloticus and O. aureus. R eproductive performance was assessed in the females, in the developing eggs and in the resultant offspring, in an attempt to determine the optimum nutrition for successful spawning of O. niloticus and O. aureus. The reproductive response of O. niloticus and O. aureus to alpha-tocopherol acetate was nearly the same regarding egg number and quality, hatchability, gonadosomatic index and quality of the resulting offspring,Results revealed that alpha-tocopherol acetate greatly improved not only egg and sperm quality but also seed production. None of the three levels of alpha-tocopherol acetate had any obvious effect on the mean relative fecundity of either O. niloticus or O. aureus. Females of both strains that fed on a diet supplemented with 50 mg «-tocopherol acetate/kg produced larger eggs than females of the control that fed on diet without supplemental alpha- tocopherol, or on diets supplemented with lower levels of a -TOH, The highest mean hatching percentage and lowest mean percentage of deformed larvae were observed in eggs extruded from females fed 50 mg a-TOH/kg-supplemented diet in both strains. While lower mean values of hatching percentage and higher mean values of deformed larvae percentage were detectable in eggs of those females that were fed supplemental 25 and 5-mg a-TOH/kg diet. Fry of the third treatment attained the highest mean body weight. The smaller sizes of fry were obtainable from eggs produced by females fed the lower levels of a-TOH. Fry of females that fed tocopherol -free diet was the smallest. Females that fed on diets provided with higher levels of