The "bayonet" deformity from poliomyelitis is a peculiar type of deformity of knee. From January 1986 through December 1994, 23 cases of this type of knee deformity were corrected by surgery. The operative procedures performed were suprachondylar osteotomy of femur or subplateau osteotomy of tibia. The patients were followed up from 1 to 5 years, with an average of 3 years. The result rated excellent to good was 95.6%. The features of this disorder and the main points in the surgical procedure were discussed.