The conventional osteotomies used to treat infantile tibia vara (Blount's disease) may require internal fixation and its subsequent removal. These techniques, which carry the risk of traction injury, and potential problems of stability and consolidation, do not always succeed in correcting the rotational deformity which accompanies the angular deformity. We have used a new surgical approach, the serrated W/M osteotomy of the proximal tibia, to correct infantile tibia vara in 15 knees of 11 patients. We present the results in 13 knees of nine patients who have been followed up for a mean of eight years. The mean angular correction achieved after operation was 18 +/- 5.8 degrees. The mean femorotibial shaft angle was corrected from 14.2 +/- 3.7 degrees of varus to 4.6 +/- 4.4 degrees of valgus. At the last follow-up, the mean angular correction had reduced to 1.3 +/- 4.9 degrees of valgus without compromising the rotational correction and the overall good clinical results. All the patients and parents were satisfied, rating the result as excellent or good. There were no major postoperative complications and no reoperations. Eight patients were free from pain and able to perform physical activities suitable for their age. One complained of occasional pain. This procedure has the advantage of allowing both angular and rotational correction with a high degree of success without the need for internal fixation.