To determine the potential risk of transfusion malaria at the Hospital Militar Central in Bogota, Colombia, sera from 3114 blood donors were tested for malaria antibodies by the indirect ELISA technique. Positive results were found in 8.6 per thousand of the serum samples using P. falciparum antigen containing more than 60% mature forms as substrate. Three cases of transfusion-induced malaria were confirmed during the study. The first patient developed a P. vivax infection one week after the administration of one unit of infected blood. The other two patients received a red blood cell concentrate and a platelet preparation, respectively, derived from a single donor and developed a P. falciparum infection eight days after transfusion. The application of the ELISA technique would be of use in attempts to control transfusion-induced malaria.