The Women's Health Study of Accra is a population-based cross-sectional survey that was conducted between March and September 2003 to assess the burden of disease in women in Accra. In addition to data relating to general health and living conditions, data on age at first menstruation was collected during the survey. A retrospective cohort analysis of the reported age at menarche was conducted using data from 2,644 women aged between 18 and 100 years. The median age of first menstruation of the entire cohort was 15.5 years and the median age of first menstruation among those aged <20 was 14.5 years. There was a statistically significant difference in median age at menstruation among the different age and socioeconomic groups. Multiple linear regression showed a significant decline of 0.2 years per decade in the mean age at menarche among Ghanaian women.