Anaemia in pregnancy is associated with maternal morbidity and mortality and is a risk factor for low birth-weight. Of 507 pregnant women recruited in a community, cross-sectional study in southern Tanzania, 11% were severely anaemic (<8 g haemoglobin/dl). High malarial parasitaemia [odds ratio (OR)=2.3] and iron deficiency (OR=2.4) were independent determinants of anaemia. Never having been married (OR=2.9) was the most important socio-economic predictor of severe anaemia. A subject recruited in the late dry season was six times more likely to be severely anaemic than a subject recruited in the early dry season. Compared with the women who were not identified as severely anaemic, the women with severe anaemia were more likely to present at mother-and-child-health (MCH) clinics early in the pregnancy, to seek medical attention beyond the MCH clinics, and to report concerns about their own health. Pregnancy-related food taboos in the study area principally restrict the consumption of fish and meat. Effective anti-malaria and iron-supplementation interventions are available but are not currently in place; improvements in the mechanisms for the delivery of such interventions are urgently required. Additionally, opportunities for contacting the target groups beyond the clinic environment need to be developed.