Pellagra was in existence for nearly two centuries in Europe before being recognized in the United States, where it was first reported in 1902. Over the next two decades, pellagra occurred in epidemic proportions in the American South. Poverty and consumption of corn were the most frequently observed risk factors. Since the exact cause and cure of pellagra was not known, a culture of "pellagraphobia" formed among the public. Patients were shunned and ostracized. The medical community implicated spoiled corn as the cause of pellagra, which had economic repercussions for agriculturists. Joseph Goldberger, MD, of the United States Public Health Service eventually solved the secret of the malady: faulty diet. Goldberger was able to prevent and induce pellagra by dietary modification, a landmark event in the annals of medicine, nutrition, and epidemiology. His work and the social history of that period are reviewed.