Pyoderma gangrenosum (PG) is an inflammatory ulcerative condition of unknown etiology. An autoimmune mechanism including immune complex-mediated neutrophilic vascular reactions has been suggested. The role of tumor necrosis factor (TNF) in PG remains unclear. Evidence supports the idea that TNF plays a role in chronic inflammation and migration of neutrophils to these lesions. PG is frequently associated with various diseases, but up to 50% of cases are idiopathic. There are several reports describing the successful use of infliximab (Remicade, Centocor, Inc, Horsham, Pa), a chimeric antitumor necrosis factor alpha monoclonal antibody, in the treatment of inflammatory bowel disease- associated PG, but there have been few reported cases of infliximab in the treatment of idiopathic PG. The authors present a dramatic improvement in 4 cases of idiopathic PG of the lower leg treated with infliximab.