Radiographs of 19 dogs diagnosed as having malignant histiocytosis were examined. The most common abnormalities involved the spleen (10), liver (6), lymph nodes (6 thoracic, 4 abdominal), and lungs (6). Other abnormalities involved the spinal column (3), and bones (2). Correlations were made between radiographic appearance and histologic diagnoses. As has been reported, Bernese Mountain Dogs were found to be significantly more often affected than other breeds. Rottweilers and Golden Retrievers were also found to have higher incidence rates. Viewed radiographically, treatment appeared to have little impact on the course of the disease.