Twelve patients with florid reactive periostitis of the small bones of the hands and feet are presented. Clinically, the lesion usually presents as a swelling of the affected part, sometimes accompanied by pain, tenderness, and redness. Histologically, the lesion may be mistaken for benign and malignant neoplasms such as osteosarcoma or parosteal osteosarcoma or osteochondromas. The features that distinguish reactive periostitis from the several diagnostic possibilities are presented. It is important for the clinician and the pathologist to recognize the existence of florid reactive periostitis in the hands and feet and to treat accordingly. Local excision appears to be adequate treatment; follow-up indicates little risk for local recurrence.