Damage to intestine is a serious problem after accidental radiation. To examine substances to ameliorate damage by post-irradiation administration, we focused on the regeneration process following irradiation to intestine. Using experimental systems to examine the regeneration, effects of clinically used sex hormones were compared. An anabolic steroid, nandrolone (19-nortestosterone), stimulated proliferation in IEC-6 epithelial cells. Single injection of 19-nortestosterone ester with prolonged action to mice 24 h after abdominal irradiation at lethal dose of 15.7Gy showed significant life-saving effect. Regeneration indicators as microcolonies of BrdU-incorporated cells at Day 5 and c-myb mRNA expression levels at Day 4 were enhanced by 19-nortestosterone administration. In contrast, high concentration of estradiol inhibited growth of IEC-6. Introduction of estradiol ester to abdominally irradiated mice decreased levels of regeneration indicators and survival rate. These results suggest the effectiveness of anabolic steroid as well as the importance of manipulation of steroid receptors in the recovery of mucosa damaged by radiation