A microplate ELISA was developed to measure C-reactive protein (CRP) and it was used to establish the relationship between CRP levels and malaria. Highest serum CRP levels were found in African patients with high Plasmodium falciparum parastaemia. However, even African children with lower parasitaemia had higher CRP levels than others without parasitaemia. All African groups studied had CRP levels above those of a control UK group.