The main objective of the present study is to investigate some genetic aspects such as estimates of heritabilities, genetic and phenotypic correlations between body weight and body gain, genetic gain and heterotic effects of (Nzwzealand) white and (California) rabbits and their crosses. Results obtained could be summarized as follows: Heritability estimates for body weights were high and moderate at 4, 6, 10 and 12 weeks in NZW rabbits, and at 4 weeks in Cal rabbits. The values of NZW rabbits were 0.58, 0.63, 0.53 and 0.43, respectively. In Cal rabbits, the corresponding value was 0.61. The estimates of genetic correlation between records of the different post-weaning body weights and growth rates at different age stages were high and positive in NZW rabbits. Estimates of direct heterosis for body weight was mostly positive and evidenced the existence of heterotic effect as a result of crossing between NZW and Cal rabbits. The heterotic effect was significant (P<0.01) on body weight at 4,6,8,10 and 12 weeks of age, and growth rate during 4 -6, 6-8, 8-10 and 4 -12. Maternal additive effect on post-weaning growth rate was in favour of NZW dams, and significant differences (P<0.01) during 4-6, 6-8 and 4-12.