To evaluate the efficacy of modified Ranawat soft tissue balance technique on total knee arthroplasty (TKA).From January 2004 to June 2008, 34 cases (44 knees) of valgus deformity were treated with TKA. There were 5 males (5 knees) and 29 females (39 knees), aged 55-79 years old (average 60.3 years old) and including 18 left knees and 26 right knees. The deformity was caused by osteoarthritis in 9 cases, by rheumatoid arthritis in 19 cases, and by traumatic arthritis in 6 cases. According to Ranawat classification, there were 5 cases (5 knees) of type I and 29 cases (39 knees) of type II. All patients were performed modified Ranawat soft tissue balance technology.The operative time was (65 +/- 7) minutes. Burst fracture of femoral condyle occurred and internal fixation was selected in 1 case of rheumatoid arthritis. Small incision necrosis occurred and healed after debridement in 1 case of rheumatoid arthritis. Incision healed by first intention in other cases. Adhesions occurred in 1 case (1 knee) and hydrarthrosis in 4 cases (4 knees), all cured after symptomatic treatment. All patients were followed up 6 months to 5 years with an average of 2.6 years. All patients had no complications of deep vein thrombosis, dislocation, vascular injury and nerve injury. X-ray films showed no signs of prosthesis loosening and infection at 1 year after operation. The X-ray films showed statistically significant differences (P < 0.05) in anatomic valgus angulation between preoperation and 1 week after operation [(25.4 +/- 3.1) degrees vs (3.8 +/- 1.2) degrees]. There were statistically significant differences in modified KSS score between preoperation and 1, 2 years postoperatively (P < 0.05).It is a simple and effective way to treat the valgus deformity with modified Ranawat soft tissue balance technique in TKA, which can achieve the satisfactory results in the knee stability, the range of motion and the deformity correction.