Japanese quail embryos were cultured in mineral rich (MR) using chickens egg shell and mineral-free (MF) using Saran Wrap cultures after 2.5 days of normal incubation. In the MR culture, 82% of embryos survived beyond 14.5 days of incubation and 3 embryos out of 93 (3%) hatched. In the MF culture, 80% survived beyond 9.5 days and 59% beyond 14.5 days. Mineral content (Ca, Mg, K, and Na) of the embryos and of the residual matter within the egg (remaining egg contents excluding the embryo, shell, and shell membrane) were analyzed at 7 to 15 days of incubation. Calcium content of the embryos increased gradually between 9 and 11 days and showed a rapid increase after 11 days in both normal incubation (control) and MR culture. Changes in mineral levels of the embryos plus residual matter within the egg were as follows. Calcium content of the controls increased gradually between 9 and 11 days and showed a rapid increase after 11 days. In MR cultures, Ca increased between 10 and 12 days and showed a rapid increase after 12 days. Magnesium content increased rapidly after 13 days in controls and showed a small increase after 13 days in MR cultures. Potassium and Na content remained constant in both controls and MR cultures. In MF cultures, content of the four minerals remained constant throughout the culture period. Mineral levels of Japanese quail and chicken eggs were compared before and after normal incubation. It was found that 81.5% of Ca and 30.8% of Mg assimilated by newly hatched quail chicks were derived from the egg shell during incubation and 84.2% of Ca and 23.5% of Mg in the chicken.