Seventy-eight premenopausal women affected by benign endometrial hyperplasia (60 simple and 18 complex) were treated from the 10th to the 25th day of the menstrual cycle with a vaginal cream containing 100 mg of natural micronized progesterone in polyethylene glycol base. The treatment lasted 3 months in 58 patients and 6 in the other 16 patients. Four patients were lost from the study. We observed a total of 67 complete regressions (90.5%) of which 58 (78.3%) occurred in the first 3 months and 9 (11.5%) after 6 months of treatment. Simple hyperplasia showed a significantly higher response to treatment in comparison with the complex type (P < 0.001). The most frequent endometrial pattern detected in the patients in whom hyperplasia regressed was of a secretive type. Recurrence of hyperplasia occurred in 1 out of 58 (1.72%) patients at the 3rd month and in 3 out of 49 (6.1%) patients at the 6th month after treatment. There were no significant differences between the two hystological groups in the percentage of recurrence. During treatment we observed a significant reduction of the amount, duration and frequency of the menstrual bleeding. Minimal side-effects were observed. In conclusion, for its effectiveness and safety, vaginal administration of natural micronized progesterone seems to be an interesting approach to benign endometrial hyperplasia, particularly indicated in women also affected by metabolic disorders.