We present a case-control study to investigate the distribution of Plasmodium falciparum genotypes in patients with severe and mild malaria. We compared clinical and parasitological data with the parasites' genotype and rosetting. The study group consisted of 100 children suffering severe malaria, defined as severe anaemia and hyperparasitaemia. These children were matched by age, sex and provenance with 100 children with mild malaria. For characterization of the parasites we used the polymerase chain reaction to determine merozoite surface antigen (MSA) 1 and 2 genotypes and the phenomenon of rosette formation. We found a significant association between rosette formation and disease severity, and a significant association of severe anaemia with the presence of the MSA-1 allele K1. Infections with 2 genotypes in the severely affected group were significantly associated with severe anaemia and the presence of MSA-1 allele K1. Comparison with the findings of other groups led to the conclusion that the occurrence of P. falciparum genotypes seems to differ geographically.