In summary, the foot is generally not a common site for the occurrence of squamous cell carcinoma. However, since the foot may more frequently be the site of osteomyelitis, one must not ignore the possibility of a squamous cell carcinoma developing as a secondary complication of a chronic draining osteomyelitic sinus. In recent years antibiotics have greatly decreased the incidence of chronic osteomyelitis, but have not proved to be the sole answer to bone infections. In treating recalcitrant ulcers of unknown etiology that have not responded to conventional modes of therapy, malignancy must be ruled out, especially in light of a foul odor, enlarging mass, increasing pain, and bleeding or radiographic evidence of increased bone destruction. Early roentgenographic examination may be the key factor in determining whether the squamous cell carcinoma is, in fact, a primary lesion or rather a secondary complication of chronic osteomyelitis. The destruction of bone in squamous cell carcinoma secondary to osteomyelitis is due largely to bacterial infection rather than neoplastic invasion (17). Invading bacteria are thought to break down the natural barriers and allow the neoplasm to enter as a secondary invader; necrotic bone is then replaced by neoplastic bone (4). It is impossible to differentiate grossly or roentgenographically between necrotic bone due to infection and neoplastic bone due to malignancy. Therefore it is imperative that these lesions be biopsied to insure accurate diagnosis and adequate therapy and follow-up.