Previous reports on antimalarial toxicity have only been related to long-term continuous treatments for nonmalarial indications, which require prolonged use of large doses, up to 1000 g or more every year. We describe a patient with recurrent malaria, prophylactically treated with low-dose chloroquine, who developed heart failure due to biventricular cardiac dysfunction. The right ventricle endomyocardial biopsy was suggestive of chloroquine toxicity. The heart failure improved after drug withdrawal. As a consequence, the potential for reversibility and the severity in undiagnosed cases of these toxic cardiomyopathies emphasize the importance of recognizing early signs of toxicity in order to withdraw antimalarials before the occurrence of life-threatening cardiac toxicity.