Tanzania is an area of moderate to high risk for severe anaemia during pregnancy. There is extensive literature examining the consequences of severe anaemia for pregnant women, but the impact this problem has on their infants in malaria-endemic regions is poorly understood. Between 1999 and 2001 we used a demographic surveillance system in the Kilombero Valley, Tanzania to link morbidity and socio-economic status data for 301 pregnant women to the survival of 365 days of their singleton babies, looking for evidence of an association between infant mortality and maternal haemoglobin (Hb). The hazards ratio for infant mortality amongst women who had been severely anaemic in pregnancy (Hb < 8 g/dl) was 3.1 [95% confidence interval (CI) 1.1-9.1, P = 0.04] compared with women with Hb above this level after controlling for other factors. Prevention of anaemia in pregnancy may lead to an improvement in infant survival.