We compared the clinical-radiographic presentations of bacteriologically proven tuberculosis in 72 elderly (mean age: 71 yr) and 73 younger patients (mean age: 39 yrs). The tuberculin test (2 TU PPD) was positive in 55% and 92%, respectively. The prevalence of cough, dyspnea, anorexia, and weight loss was higher in the elderly (p less than .05), and night sweats were more prevalent in the younger patients (p less than .01). The radiographic pattern was not different between both groups (p greater than .10): "usual" apicoposterior lesions (with or without other abnormalities) were found in more than 70% of both groups; isolated "unusual" lesions consisted in both groups mainly of anterobasal infiltrations and sometimes of pleural effusions, rounded nodules, or miliary patterns. Yet, initially a wrong diagnosis was made more often in the elderly (p = .05). Malignancy, chronic pulmonary disease, and immunosuppression were more frequently encountered in the elderly (p less than .05), whereas alcoholism and smoking were more frequent in the younger patients (p less than .001). Tuberculosis-related mortality occurred in 6 elderly and 1 younger patient.