Hematologic malignancies including acute leukemias rarely associate with cystic fibrosis (CF). In this paper, we describe a case who was diagnosed with CF when she was three months old and presented with acute myelogenous leukemia (AML) at the age of 17 years. Although she received reduced doses of chemotherapy because of her clinical status she responded well. She is the first CF patient who developed AML in our department among 296 CF patients over a 22-year period.