It was reported that a complete antifertility action of alpha-chlorohydrin in combination with glycidol in male rats after a daily oral dose of 5mg/kg and 75mg/kg respectively for two days. Simultaneously some ultrastructural changes including mitochondrial swelling, atrophy of Golgi complex, decreasing in pinocytotic vesicles and stereocilia were found in principal cells of epididymis within 3 days after medication.In this experiment the animals received 3, 6 and 9 courses of treatment respectively, each course included two days of administration with a daily dose mentioned above and eight days of cessation of medication.The specimens of initial segment of epididymis, liver and kidney were taken at the end of 3 rd, 6 th and 9th courses of treatment for electron microscopy.The principal cells of initial segment of epididymis revealed a normal feature at the end of 3 rd and 9 th course of treatment. But at the end of 6 th course of treatment, the atrophy of Golgi complex and the decrease in stereocilia and pinocytotic vesicles were found in some principal cells.Any ultrastructural changs of sperms in the initial segment were not found by electron microscope.There was also mitochondrial changes with striking increase in the density of the matrix and reduction of size in some liver cells at the end of 6 th course of treatment, but not at the end of 3 rd or 9 th course of treatment. The epithelial cells of nephron in all the specimens revealed a normal ultrastructural feature.The results suggest that the ultrastructural changes of the principal cells and the liver cells induced by the mixture of the drugs could be recovered at the end of treatments.