Pyoderma gangrenosum (PG) is a debilitating skin disease most often associated with inflammatory bowel disease and is a reportedly rare cause of peristomal ulceration. The lesions of PG rapidly evolve from small, erythematous pustules to deep, painful, pyogenic ulcers within hours to days of onset. Although the behavior and the appearance of the lesions of peristomal PG are diagnostic, a lack of familiarity with PG often leads to misdiagnosis and inappropriate therapy. This study reports four cases of peristomal PG and discusses the 20 previously reported cases in patients with inflammatory bowel disease. Seventy-five percent of patients were female and 67% had Crohn's disease. All patients had colitis, including all of the patients with Crohn's disease, 82% of whom had additional perineal complications. The diagnosis of peristomal PG was based on clinical appearance alone in 83% of cases. The onset of peristomal PG ranged from 2 weeks to 3 years following ostomy. The response to medical therapy was variable. All cases (17 of 17) treated with high-dose corticosteroids and local wound care responded, but five cases required additional therapy. No patient was successfully treated with stoma revision. Risk factors for the development of peristomal PG include Crohn's colitis, female gender, and perineal disease. While most patients respond well to systemic steroids and local wound care, up to one third of patients require long-term medical management.