It is generally accepted that ectopic bone should be removed after full maturation. Removal of immature ectopic bone was attempted combined with immidiate postoperative irradiation to suppress its recurrence. The authors report two cases immature heterotropic bone resection around elbow joint followed by 2000 Rad midplane irradiation given in ten fractions over fourteen days. The results obtained are as follows: 1. There was no evidence of recurrence after removal of immature ectopic bone. 2. Improved range of joint motion was observed during 3 months and 6 months posteroperatively.