The aim of the performed investigations was to compare eggs of Japanese quail layers of different weights with regard to their shape, selected traits of the content following various times of their storage as well as the results of hatchability and body weight of one-day old chicks. Hatching eggs were divided into four groups: group S – up to 10.50 g, group M – from 10.51 to 11.50 g, group L – from 11.51 to 12.50 g and group XL – from 12.51 g. In experiment I, on days: 1, 3, 5, 7 and 10 of storage, the following traits were assessed in 20 eggs from each group: egg weight (g) and yolk and albumen index as well as the number of Haugh units. In experiment II, five hatches were carried out. The total of 480 eggs were incubated in each hatch (120 eggs for each group). On the 15th day of incubation, the eggs were weighed. After hatching, 30 chicks from each group were weighed. Basic hatchability indices were also determined. Eggs with the smallest weight, stored for 1 day, with the smallest yolks were characterized by their highest content contrary to the eggs with the highest weight (the biggest yolks but with their smallest percentage content). In eggs with the higher weight (groups L and XL), a certain increase in weight and proportion (%) of yolk was observed after 3, 5, 7 and 10 days. The highest albumen percentage content was determined in eggs from groups L and XL, whereas in the remaining groups the albumen content was the smallest. With the lengthening of the egg storage, the albumen weight did not undergo significant changes. After one-day storage, the yolk and albumen index as well as Haugh units were slightly higher for eggs of smaller weight than for bigger ones. Eggs from groups S and M were more spherical. Eggs from groups L and XL had smaller weight losses during hatching. Eggs from group L were characterized by the best fertilization, hatchability results and proportion of dead embryos and unhatched chicks. The heaviest chicks were obtained from eggs of the highest weight, while the lightest – from eggs of the smallest weight. The obtained results appear to indicate that Japanese quail eggs of 10.51-12.50 g are the best for hatching.