Number, quality, size and composition of eggs during the first 6 months (1 month = 4 weeks) of lay were analysed in two lines of meat?type Japanese quail, the HG and LG lines, divergently selected for shape of the growth curve without significant changeof adult body weight. The results showed that the genetically determined shape of the growth curve is an important factor influencing the phenotypic manifestation of reproduction performance. A relatively high growth rate immediately after hatching (typical for the LG vs HG line) was associated with a low quality of eggs, especially with a high proportion of double yolk eggs. On the other hand, a high growth rate during the linear part of the growth curve was accompanied by a low number and size of eggs.