The purpose of this work was to evaluate bone marrow abnormalities in the lower limbs of patients with cystic fibrosis by means of MR imaging. Eight patients with cystic fibrosis ranging in age from 16 to 35 years (average age 25.1 years) were evaluated with MR imaging of the lower extremities. T1 weighted spin echo sequences were obtained in all patients. Pelvis, femora and tibia were imaged in the coronal plane whereas the feet were imaged in the sagittal plane. The studies were independently evaluated by two musculoskeletal radiologists. The images were not mixed with disease-free images, but the readers were completely unaware of clinical data. Distribution of haematopoietic and fatty marrow was graded on a 5-point scale. In five patients, both observers considered marrow distribution as probably or definitely abnormal relative to their age. Although our findings are very preliminary, our investigation suggests that cystic fibrosis may be added to the list of disorders in which bone marrow abnormalities may be observed.