The inclination of the joint line after supracondylar osteotomy of the femur for valgus deformity was studied in 22 patients and 26 knees. The patients (four males and 18 females) were 17-77 years old (mean, 49.5 years). The obliquity of the joint line was measured in positive degrees (medial inclination) and negative degrees (lateral inclination). Mean obliquity was +3.1 degrees in the pre-operative study and -2.0 degrees in the post-operative study. A more horizontal joint line was obtained following surgical treatment (mean correction: 5.0 degrees ).