Squamous cell carcinoma is a primary malignant tumor of the skin arising from the epidermis with etiology unknown, and chronie irritations are considered as predisposing factors such as prolonged exposure to sunlight, chronic ulceration of the scar, persistent draining sinus of the chronic osteomyelitis. Habitual pipe smoking and exposure to heavy metal or chemical agents are also thought to be contributing factors to produce this tumor. Orthopaedic surgeons are occasionally concerned in case of patients with squamous cell carcinoma developed in the extremities particularly arising from the persistent draining sinus of the chronic osteomyelitis. We reviewed 12 patients with squamous cell carcinoma in the extremities treated at National Medical Center between 1963 and 1975. All cases were definitely diagnosed clinically and histopathologically. 1) Male to female ratio was 11:1. Average sge of the patients was 52. 2) Farmer is predominant in incidence as 10 out of 12. 3) Sites of invoIvement were buttock and lower extremities in all cases. 4) Predisposing factors of the tumor were chronic skin ulceration in 7 cases, persistent draining sinus of chronic osteomyelitis in two and unknown in three cases. 5) Duration of the skin ulceration or draining sinus before producing tumor was considerably long between 10 and 30 years in majority of the cases. 6) Duration of newgrowth before operation was less than one year in 5, between one and two years in three, and more than two years in four cases. 7) Pre-operative chest X-ray was normal in all cases. However X-ray of the bones of affected limbs showed no bony change in two cases, and various bony changes in 10 cases such as periosteal reaction, cortical erosion, findings of pre-existing chronic osteomyelitis etc. In detail, two cases revealed direct infiltration and active bony destruction into the cortex and medulla by tumor mass. 8) We performed amputation or disarticulation at various levels in 5 cases, radical excision in 3 and biopsy in one case. 9) Within 6 months postoperatively, four cases showed local recurrence of newgrowth as well as metastasis to the lung concomitantly. Three of them were the cases of radical resection. One of them developed distant metastasis to the clavicle.