A statistical study was carried out on a cohort of 165 women, menopausal for at least 2 years, who had undergone reductive ovarian surgery in fertile age, against nonoperated controls. The purpose of the study was to examine possible interference caused by surgery on fertility performance and age at which the natural menopause starts. It was found that fertility in the operated women was reduced when compared to the controls, although the difference was not of statistical significance. However, the difference between the two groups in mean age at menopause onset was significant (P < .001). The study sample was divided into two sub-groups according to age at operation (<30/>30) and a significant difference between them was found for age at menopause onset, the under-thirty group starting earlier. In particular, the onset of menopause was even earlier in women who had undergone bilateral wedge biopsy for polycystic ovarian syndrome (PCO). The anatomical state of the ovary at operation was also found to be relevant: ovariectomized women with intrinsic ovarian pathology (cysts, tumors or PCO) started the menopause earlier than those without intrinsic diseases (i.e., ectopic pregnancy), suggesting that such intrinsic pathology may cause a primary depletion of the follicles.