AIM and METHODS: The purpose of the study was to characterize the time-related effect of Danazol therapy on endometriosis explant using the rat model. Endometriosis was induced in mature female rats. One group of treated animals as well as controls were sacrificed at 2,4,6 and 8 weeks after treatment at which time the explant was evaluated. RESULTS: Explant volume was significantly reduced in all treatment groups, and the effect was more significant in animals treated for 4 weeks than those treated for only 2 weeks. CONCLUSION: Danazol treatment can cause gradual regression of endometrial explant in a time-related manner.