This study was carried out to determine the effect of live weight, male to female ratio and breeder age on egg weight and the hatching characteristics in Japanese quails (Coturnix coturnix japonica). Female quails at the age of six weeks, were weighed individually and separated into three weight groups depending on their live weights. The groups were classified as light (170-200 g), medium (201-230 g) and heavy (> 230 g). The male quails to be mated with these groups were selected from the individuals with mean live weight of 200-220 g. Groups were placed in the pens at male : female ratios of 1: 1, 1:2, 1:3, 1:4 and 1:5. Egg weight was significantly lower in the light group compared with the eggs obtained from the females with medium and heavy live weight. Egg weight increased in accordance with increasing breeder age. Live weight, male to female ratio and breeder age had a significant effect on fertility and hatchability. Fertility increased with an increase in live weight. The highest fertility was found in the group with male to female ratios of 1:2 and 1:3. Fertility at the ages of 11-14 and 15-18 weeks was higher than those of 7-10 and 19-22 weeks of age.