The aim of the study was to analyze eggshell temperature, embryo viability, and hatchability parameters of broiler breeders at different ages (26-30, 31-35, 36-40, 41-45, and 46-64 weeks). A total of 33,150 eggs from Ross 308 broiler breeders collected from commercial flocks were used to analyze the following: egg weight and egg weight loss during 18 days of incubation; eggshell temperature controlled on days 3, 14, and 18 of incubation; number of infertile eggs including eggs with dead embryos at early stages of development, that is, in the oviduct or after oviposition; the total percentage of embryonic mortality and the percentage of embryonic mortality at different times of incubation; unhatched, dead after hatching, and culled chicks as well as hatchability percentage from fertilized eggs. The hatchability results of Ross 308 broiler breeders were high from the beginning of reproductive season till the 40th week. However, the study failed to reveal any relationships between hatchability and the egg weight, average temperature of the shell, and egg weight loss during incubation period. The oldest hens, over 45 weeks of age, had the highest mortality of chicks and the greatest share of unhatched chicks.