Anaemia during malaria is not completely understood. Fourteen cases of antierythrocyte autoimmunisation with anti-I specificity were investigated in a Paris hospital during a period of 2 years. The patients lived in Gabon and had not been taking antimalarial chemoprophylaxis. All had chronic malaria (strongly positive antimalarial immunofluorescent antibody tests). All the recognised caused for anti-erythrocyte autoimmunity were excluded. One possible explanation for these observations is some sort of interaction between I antigen and Plasmodium, the result of which facilitated penetration of the erythrocyte by the malarial parasite.