Remarkable improvement in control of malignant tumor was achieved by combined surgery and postoperative radiation therapy. In Past, radiation therapy had been recommended after 4-6 weeks from operation because of worry about increased complication rate of sugical wound by post-operative irradiation. Nowadays, early surgical extirpation and early post-operative irradiation is recommended for better therapeutic effect. To evaluate the relationship between surgery-radiation interval and healing of surgical wound, an experimental study was undertaken using a total of 132 mice. A single dose of 2000 rads irradiation was delivered immediate after and on 1, 3, 5, 10, 14 days after incision and suture on the skin of hindlimb of mice. Tensile strengths of the wounds were measured after removal of stitches on 1st, 3rd, 5th, 7th, 10th, 14th and 21st post-operative days. The results are summarized as follows: