The objective of the present study was to determine median age at natural menopause using the status quo method and the sociodemographic and reproductive variables that determine the age at natural menopause in Peruvian women from Lima and Cerro de Pasco. The study was performed in one urban area from Cerro de Pasco (4,340 m above sea level) and in one urban area from Lima (150 m above sea level). The total sample was 469 women aged 28-56 years, 216 from Cerro de Pasco and 253 from Lima. Median age at menopause was 47.1 years at sea level, and 46.14 years at high altitude (p = 0.0005). Results of the proportional hazard regression analysis showed that life at high altitude and lack of use of oral contraceptives were factors associated with early age at menopause, whereas later age at menarche and higher chronological age were associated with delayed age at menopause. In conclusion, altitude is a factor that independently accelerated age at natural menopause. © 1997 The North American Menopause Society.