During the past eight years we have observed 56 histologically proved cases of bronchiogenic carcinoma; 37 came to necropsy (an incidence of 2.5 per cent of all necropsies in this period), and in the remaining 19 the antemortem diagnosis was established by biopsy. We have evaluated the clinical and pathologic features of this material. CLINICAL FEATURES Age and Sex.— As may be seen in table 1, 88 per cent of the patients were men and the average age was 56, with the youngest patient 30 years of age. Duration of Illness.— The average interval (table 2) from the onset of the present illness to hospitalization was six and six-tenths months, and the average duration from hospitalization until the time of death three and one-tenth months later. It is apparent, therefore, that the disease on the average had consumed two thirds of its span before hospitalization occurred. Moreover, in 22