Intravascular haemolysis, particularly blackwater fever is a rare but severe clinical syndrome, occurring after ingestion of antimalarials. A resurgence of this affection which occurred frequently during the colonization has lately been noticed. We have conducted a prospective study in order to identify the main antimalarials which are responsible for this syndrome. We reported 41 cases from 1996 to 2000, among which 80% of blackwater fever cases were associated with quinine ingestion or similar structural molecules. Their causal role is well established. For the other molecules it is difficult to underscore their role. The mortality rate is around 18%. The morbidity is high because 90% of patients have suffered from renal failure. Among them, 47% required dialysis. We are facing a public health issue thus a rational use of antimalarials is necessary.