This study was designed to estimate the additive genetic, heterotic, and maternal effects on harvest body weight and survival of tilapia (Oreochromis niloticus) combinations in a 4x4 complete diallel cross involving four populations, i.e. NOVIT, GIFT, China, and the Philippines. Mass spawning method was applied to produce hybrid combinations (with 60 males and 60 females per cross) for testing on harvest body weight and survival at three locations, Quang Nam, Tien Giang and Bac Ninh. A total of 8,001 Nile tilapia was evaluated after a grow-out period of 6 months. A linear mixed model was used to estimate strain additive genetic, heterotic, and maternal effects for body weight and survival at harvest. Research results showed that the non-additive genetic (heterotic) effects were small and not significantly different from zero for the traits studied, whereas the additive genetic effects were statistically significant (P <0,001). Based on heterotic and additive genetic effects among crosses, pure crosses between Novit and Novit showed the highest additive genetics effects, while different strain cross between Novit and the Philippines indicated the best additive genetics effects.