Introduction : Growth and survival are the life-history traits of the most interest for oyster production since they determine biomass output (growth x survival). This study aimed to investigate whether there is genetic basis for growth, survival and their plasticity to know if a selection program is conceivable for these traits. Material and Methods : Nested half-sibs mating design was used to produce families of oysters: 5 males were each mated to three females producing 5 half-sibs families, each containing 3 full-sib families. At 15 months of age (May 1999), each full-sibs family was randomly split into five groups which were given different treatments. Two groups were placed in a constant environment: one with low food resources and another with high food resources. The three other groups were regularly transferred from the first environment to the second one according to different periods: a group was transferred every 15 days, another every month and the third every 2 months. Oysters were individually monitored for growth and survival every 15 days over 6 months (from May to October 1999). Both crossed and nested analyses of variance enabled us to determine genotypic and environmental effects on growth and survival. Results : The analysis of variance revealed significant genotypic and environmental effects (p<0.0001) but also significant genotype x environment interaction (p<0.0001) for growth. Analysis on survival will also be presented. These results represent a first step toward a possible selection program for the studied traits.