Many cases of severe malarial anaemia are clinically stable, but some can deteriorate rapidly. In a cross-sectional survey of 255 children with clinically stable malarial anaemia, 72 had severe anaemia (PCV < or = 15%) and 183 were moderately anaemic (PCV < 15-21%). Being female, or febrile, or a referral and having low parasitaemia or hepatomegaly were the risk factors for severe anaemia.