A 62-year-old female was diagnosed as having acute lymphocytic leukemia in October 2001. She achieved complete remission after induction therapy with L-asparaginase, doxorubicin, vincristine and prednisolone. However, an invasive fungal infection developed in the lung, followed by a sudden complete atrioventricular block. Her heart rate was brought back to normal by the administration of isoproterenol. In spite of anti-fungal therapies, the patient finally succumbed to pneumonia in January 2002. Autopsy revealed an invasion of fungi into the lung, mitral valves and atrioventricular node. We need to pay attention to such a cardiac complication when an immunocompromised host suffers from an invasive fungal infection.