The Muslims of Aligarh city are predominantly Sunnis, although there are also a considerable number of Shias. Among the Sunnis, approximately a quarter belong to Syed, Sheikh, Moghal and Pathan groups, and three-quarters belong to various lower biradaris. In the present study, 304 women attending the Primary Health Centre of the J. N. Medical College and Hospital, Aligarh Muslim University, Uttar Pradesh, were surveyed and the following recorded among Muslim women of high-rank (Ashraf) and low-rank (Ajlaf) castes: incidence of marriage, age of the mother at the time of marriage, present age of the mother, abortions, still births, pre-reproductive mortality and overall mortality. The Ashraf are comprised of the Sheikh, Syed and Pathan, whereas the Ajlafs have Qureshi, Saifi and Ansari biradaris. Maternal age was scored as above and below 45 years in each biradari. Significant effects of maternal age were seen on mortality of offspring, whereas populations did not show consistent differences, except when Ashrafs and Ajlafs were considered separately. The results show higher mortality and abortions for various groups. This may be due to various biological and socio-cultural factors, including hidden inbreeding in the remote past.