Prenatal iron supplementation may improve pregnancy outcomes and decrease the risk of child mortality. However, little is known about the importance of post-natal maternal iron status for child health and survival, particularly in the context of HIV infection. We examined the association of maternal anaemia and hypochromic microcytosis, an erythrocyte morphology consistent with iron deficiency, with child health and survival in the first two to five years of life. Repeated measures of maternal anaemia and hypochromic microcytosis from 840 HIV-positive women enrolled in a clinical trial of vitamin supplementation were prospectively related to child mortality, HIV infection and CD4 T-cell count. Median duration of follow-up for the endpoints of child mortality, HIV infection and CD4 cell count was 58, 17 and 23 months, respectively. Maternal anaemia and hypochromic microcytosis were associated with greater risk of child mortality [hazard ratio (HR) for severe anaemia = 2.58, 95% confidence interval (CI): 1.66-4.01, P trend < 0.0001; HR for severe hypochromic microcytosis = 2.36, 95% CI: 1.27-4.38, P trend = 0.001]. Maternal anaemia was not significantly associated with greater risk of child HIV infection (HR for severe anaemia = 1.46, 95% CI: 0.91, 2.33, P trend = 0.08) but predicted lower CD4 T-cell counts among HIV-uninfected children (difference in CD4 T-cell count/µL for severe anaemia: -93, 95% CI: -204-17, P trend = 0.02). The potential child health risks associated with maternal anaemia and iron deficiency may not be limited to the prenatal period. Efforts to reduce maternal anaemia and iron deficiency during pregnancy may need to be expanded to include the post-partum period.