The main objective of the present study is to estimate some genetic aspects such as heritabilities, genetic and phenotypic correlations among litter size and weight traits, genetic gain and heterotic effects of (NZW) and (Cal) rabbits and their crosses. Results obtained could be summarized as follows: Heritability estimates for litter traits were high and moderate of both NZW and Cal rabbits. All the possible genetic correlations among litter traits in both NZW and Cal rabbits were positive and moderate to high values. All litter traits studied were higher in (Cal) buck x (NZW) doe rabbits than those of other mating groups (NZW buck x Cal doe). The Cal sired mating groups produced litters with larger size (litter size at birth) and heavier weight (litter weight at birth and litter weight at weaning) as compared to NZW sired ones. Crossbreeding between NZW and Cal rabbits was associated with a significant positive heterotic effect on all litter traits studied. Direct heterotic effect was significant (P<0.01) on LSB, NBA, LSW, LWB and LWW. Maternal additive effect in Cal rabbits was significant (P<0.05 or P<0.01) for LSW, LWB and LWW and consequently could be used as a breed of sire in crossbreeding programs when using both NZW and Cal rabbits. Generally, the results of the present study may encourage the breeders to improve most of the litter traits.