Pellagra is mainly caused by a niacin deficiency or its precursor amino acid, tryptophan. We report a case of a male patient, 34 years old, a chronic alcoholic with delirium tremens and gastrointestinal symptoms (diarrhea, inappetence, and heartburn). He presented erythematous-brown, scaly, and well-defined plaques dispersed throughout the integument (photo-exposed areas) for 2 months that evolved with ulceration and hematic crusts. The case was diagnosed as pellagra associated with secondary bacterial infection and treated with rest, an unrestricted diet, B-complex replacement, abstention from alcohol, restriction of sun exposure, and broad-spectrum antibiotic therapy. The treatment allowed for significant improvement of symptoms in one week. Aspects of the pathophysiology and differential diagnoses of this condition are discussed, reinforcing the importance of considering pellagra in diagnosing patients with skin lesions associated with risk factors for malnutrition.