True synovial-based hemangiomas are uncommon lesions and, as such, may enter the differential diagnosis of other lesions encountered more frequently in clinical practice, including pigmented villonodular synovitis and traumatic hemarthrosis. The consultation files of the Armed Forces Institute of Pathology were searched for benign vascular lesions diagnosed as synovial or bursal hemangiomas vascular lesions diagnosed as synovial or bursal hemangiomas submitted between the years 1960 and 1985; 20 cases of synovial hemangioma were identified. The patients ranged in age from 9 to 49 years at the time of presentation (average age, 25 years). Sixty-five percent of the patients were male; 35% were female. Presenting symptoms included pain and swelling (31%), pain alone (31%), and a painless mass (31%). Affected regions included the knee (60%), the elbow (30%), and the finger (10%). In 65% of cases the lesion was confined to the intra-articular synovium; in 30% of cases the hemangioma was located in a bursa adjacent to a joint. One case was located largely within the joint cavity but had an area of extension into the suprapatellar recess. The dominant histologic patterns included cavernous hemangioma (50%), lobular capillary hemangioma (25%), arteriovenous hemangioma (20%), and venous hemangioma (5%). One lesion (which had been incompletely excised) was removed in its entirety 3 months after the initial subtotal resection; otherwise, none of the patients studied developed recurrent disease. The clinical diagnosis of hemangioma was made in 22% of cases, while an initial pathologic diagnosis of hemangioma was reached in 67% of cases. Pathologic differential diagnostic considerations include nonspecific synovitis/bursitis, pigmented villonodular synovitis, nodular synovitis, and organizing hemorrhage. A relationship between synovial hemangioma and pigmented villonodular synovitis was not suggested by this analysis of our material.