In sub-Saharan Africa, where blood supply is critically inadequate, severe haemorrhage is a leading cause of maternal deaths. The aim of this review was to estimate the impact of lack of blood on maternal deaths and identify reasons and potential solutions. Databases and websites from 1970 to 2007 were searched for information concerning maternal deaths and near misses due to haemorrhage in sub-Saharan Africa. Original studies that provided qualitative or quantitative information about blood transfusion services in relation to obstetric deaths or near misses were included. Data about maternal haemorrhage deaths associated with lack of blood for transfusion and reasons for blood shortages were extracted from the full text of articles by two independent reviewers using predesigned, piloted forms. Twenty of 37 selected studies described a direct association between maternal deaths and lack of blood transfusions. Five of 37 provided quantitative information which showed that overall 26% (16-72%) of maternal haemorrhage deaths were due to lack of blood. Reasons included nonaffordability of blood, lack of blood donors, unwillingness of relatives to donate and inadequate supplies and transport. Lack of blood for emergency transfusions is a major, but poorly quantified and under-researched cause of maternal deaths in sub-Saharan Africa. Potential solutions include more blood donations, better financing mechanisms and more efficient management systems. Complementary approaches to prevent severe anaemia and treat hypovolaemia are important to reduce use of transfusions.