Eighty-two cases of active tuberculosis (TB) were diagnosed only at autopsy in patients hospitalized in the Chaim Sheba Medical Center during a 21-year period (1960 to 1980). Some 75 percent of the patients were over 50 years old and a large number of them suffered from accompanying diseases or drug therapy which suppresses the immune system. Diagnostic measures for the confirmation of tuberculosis (skin tests; cultures of sputum, urine, gastric juice; liver biopsy) were not taken in 75 percent of the cases. In those taken, skin tests were negative in 75 percent of cases, most probably as a sign of anergy. The rest were borderline cases in whom the diagnosis of TB was not accepted affirmatively.