We present a case of acute myeloid leukemia which went into complete remission during the course of concurrent interstitial pneumonia caused by Pneumocystis carinii. As no antileukemic, cytostatic chemotherapy had been given, it is assumed that the infection played a major role in inducing this remission, which was however of only 6 months duration. Brief reference is made to the literature concerning the effects of infections on the course of leukemia.