In an effort to reduce maternal mortality, developing countries have been investing in village-level primary care facilities to bring skilled delivery services closer to women. We explored the extent to which women in rural western Tanzania bypass their nearest primary care facilities to deliver at more distant health facilities, using a population-representative survey of households (N = 1204). Using a standardized instrument, we asked women who had a delivery within 5 years about the place of their most recent delivery. Information on all functioning health facilities in the area were obtained from the district health office. Women who delivered in a health facility that was not the nearest available facility were considered bypassers. Forty-four per cent (186/423) of women who delivered in a health facility bypassed their nearest facility. In adjusted analysis, women who bypassed were more likely than women who did not bypass to be 35 or older (OR 2.5, P </= 0.01), to have one or no living children (OR 2.2, P = 0.03), to have stayed in a maternity waiting home prior to delivery (OR 4.3, P </= 0.01), to choose a facility on the basis of quality or experience (OR 2.1, P </= 0.01), to have a high level of trust in health workers at the delivery facility (OR 2.7, P </= 0.01), and to perceive the nearest facility to be of low quality (OR 3.1, P </= 0.01). Bypassing for facility delivery is frequent among women in rural Tanzania. In addition to obstetric risk factors, a major reason for this appears to be a concern about the quality of care at government dispensaries and health centres. Investing in improved quality of care in primary care facilities may reduce bypassing and improve the efficiency and effectiveness of the health system in providing coverage for facility delivery in rural Africa.