We have shown in a retrospective analysis of 29,226 unselected children admitted to hospital on the coast of Kenya that the burden of moderate and profound or severe anaemia is substantial, affecting 15.8% of all admissions over 60 days of age, and that it carries a higher risk of in-hospital mortality (6.7–7.6%) compared to children with admission Hb >9g/dl (4%). The gene discussed is GSTM1; the disease is anemia.