The objective of the study was to evaluate the impact of birds’ sex on the carcass composition and meat (breast muscle) nutritional value in Japanese quails in a large-scale four-generation study. Standard poultry feed was used, based on maize, soya bean meal and wheat. Four generations of quails were housed up to the age of 17 weeks each. Then samples of breast muscle were collected after dissection and analysed for basic nutrient content and for fatty acids composition. Results were analysed by GLM procedure in SAS, and significance of differences between birds of different sex was estimated by Duncan's test. Dissection revealed marked differences between birds’ of different sex in case of relative organ weight. Results of meat analyses showed no differences in the basic composition. Fatty acids analyses showed a more advantageous profile in female meat.