The aim of this study was to estimate the genetic parameters associated to the environmental variability of the following traits in mice: weight at 21 days, weight at 42 days and weight gain between 21 and 42 days. Data were obtained from a experimental mice population selected during 17 generation for increase of adult weight and included 4896 males. Data were analysed using Bayesian procedures after fitting two different models: that of homogeneous variances and that of heterogeneous variances. Genetic correlation between the analysed traits and their variability was always negative ranking from -0.22 to -0.61. Results allow concluding that there is a possible genetic component affecting the analysed traits thus making possible its reduction by selection.