One thousand, two hundreds and sixty eggs of Japanese quail (Coturnix coturnix Japonica) were set into the incubator maintaining 12 treatment groups in a factorial design experiment (3 × 4) including three categories of incubated quail weight eggs (lower than 11 g., light weight (L), 11–12 g., medium weight (M) and above 12 g., heavy (H)), and four egg storage periods (1, 4, 7 and 10 days). The traits studied were egg weight loss (%) during incubation, embryonic mortality percentage, incubation time, and fertility percentages. Results obtained revealed that, there was a significant (P<0.01) increase in egg weight loss (%) with increasing egg weight during incubation while, egg storage period was insignificantly affected on the same trait. Embryonic mortality percentage during the whole incubation period (1-17 days) was significantly (P< 0.05) affected by egg weight categories as it decreased by egg weight increase where the best result was obtained with heavy eggs (H) which recorded 22.01%. A significant (P< 0.01) effect on incubation time per hour due to quail egg weight was shown while, each of the egg storage periods and interaction effects were insignificant. A significant effect (P< 0.05) on fertility percentage due to quail egg weight, egg storage period (P< 0.01), while the interaction was insignificant. The best results were with medium (M) egg weight or storage period of 1 day while the highest values (95.83 and 95.12%) were obtained by interaction of 1 day storage period with each of medium (M) or Heavy (H) weights of incubated quail eggs, respectively. Conclusively, it can be concluded that, medium quail eggs and storage periods of 1 day or 4 days gave the best results of pre-hatch performance of Japanese quail under Egyptian conditions.