Here, we measured p53 protein at E12, E13, and E15 in rat fetuses with or without spina bifida aperta, and found that p53 was significantly increased at E13 and E15 in spina bifida fetuses as compared with control fetuses, but p53 was almost the same in subgroup 2 fetuses as in controls from E12 to E15. The gene discussed is TP53; the disease is spina bifida.