Two cases are reported of a rare association of intramuscular myxoma with fibrous dysplasia in a 70 and 40 year old Japanese woman, respectively. One of them had a solitary intramuscular myxoma, and the other patient suffered from two intramuscular tumors that had been initially misdiagnosed as myxoid liposarcoma. Only 24 cases of this kind of association have been recorded in the literature. This association should be taken into consideration to avoid inappropriate treatment, when cases of myxoid soft tissue tumor with a bone lesion are encountered.