The diagnosis of primary tuberculous infection was made in a 78-year-old woman. The chest roentgenographic findings were remarkably similar to those often seen in children and adolescents with primary infection. Like the majority of adults with this entity, the patient was asymptomatic; the diagnosis was suspected epidemiologically and was confirmed by culture of M. tuberculosis from the sputum. As the incidence of new tuberculosis cases declines, the diagnosis of primary tuberculosis in the adult may be made more frequently.