A 7-month-old Myanmar boy was admitted with a 3-day history of fever. He was markedly pale and his temperature was 38·2°C. Peripheral blood smear demonstrated Plasmodium vivax infection with spherocytosis and auto-agglutination of red blood cells. Haematocrit was 16% and reticulocyte count 14·9%. Direct and indirect antiglobulin tests were positive. Antibody analysis was positive for auto-antigen I. P. vivax malaria with auto-immune haemolytic anaemia (AIHA) was diagnosed. He was treated with chloroquine and primaquine for the P. vivax infection, and oral prednisolone for the AIHA. Because of the clinical symptoms of anaemia and mild dyspnoea, blood with the least incompatible red blood cells was transfused. The clinical symptoms and signs improved. At follow-up 3 and 7 weeks after treatment, his haematocrit, reticulocyte count and peripheral blood smear results were within normal limits. Prednisolone was then tapered and stopped. The patient has since been well with no detectable recurrence of AIHA.