This study was conducted to determine the average weight loss, shell porosity, shape index and shell thickness in Japanese quail eggs during hatching process and to reveal the phenotypic correlations between hatchability and these characteristics. For this purpose, after individually weighing of the 402 eggs, eggs were weighed on 5, 10, 15 and 18 days of incubation to determine the egg weight losses. The average egg weight loss, egg shell porosity on different shell regions, shape index and shell thickness during incubation (0-18 days) were found as 19.2 %, 8.5, 77.6 % and 17.3 respectively. Statistically significant (P<0.001) positive phenotypic correlations (r = 0.491 and 0.436, respectively) were determined between egg weight loss and hatched and early dead embryos. Additionally, statistically significant (P<0.001) phenotypic correlations (r = 0.357 and 0.333) were found between the average shell porosity and hatched and late dead embryos.