Pellagra is a nutritional disease with cutaneous, gastrointestinal, and neuropsychiatric manifestations. Because of the diversity of pellagra's signs and symptoms, diagnosis is difficult without an appropriate index of suspicion. Untreated, pellagra is fatal. Two cases of pellagra in contemporary homeless people are described. Complete evaluation supported a clinical diagnosis of pellagra after exclusion of other possibilities. Signs and symptoms resolved after institution of niacin therapy and change in diet. Appropriate suspicion for a diagnosis of pellagra requires attention to a combination of socioeconomic and behavioral risk factors for nutritional deficiency. The combination of homelessness, alcohol abuse, and failure to eat regularly--particularly, failure to make use of shelter-based meal programs--may identify people at special risk in contemporary settings.