Intraosseous glomus tumors of bone are extremely rare. We report a case of an intraosseous glomus tumor of the ulna. The patient was a 25-year-old woman who had a three-month history of a palpable mass in her right forearm with spontaneous pain. Radiographs showed cortical hypertrophy and a shell-like bone formation surrounding the small osteolytic lesion within the cortex of the ulna diaphysis. The differential diagnosis included benign bone-forming tumors, such as osteoid osteoma. The patient was treated with an en-bloc resection and filling with beta-TCP. Up to one year after the operation there has been no evidence of recurrence.