This study is a correlation of radiological, surgical, and pathological findings provided by pulmonary resections of tuberculous lesions. We believe that it could apply equally well to non-tuberculous lesions requiring similar treatment. By such correlation we hope to demonstrate the importance of the radiologist's opinion and his responsibility in resections of the lung. In the past, as well as in the foreseeable future, we must assume that the radiologist is a consultant both to the internist and to the surgeon concerned with managing or treating tuberculous disease. In view of this assumption, a short summary of objectives in each of these fields may be pertinent. Three primary objectives of treatment in tuberculosis may be expressed as follows: (1) closure of cavities; (2) conversion of sputum to negative; (3) stabilization of tuberculous infiltrations. These objectives have been the same down through the ages; yet chemotherapy has so greatly changed the results of treatment that special mention of its effects is worth while. Chemotherapy at first was limited to streptomycin given alone. It was found, however, that resistance to the drug developed in 80 to 90 per cent of cases. It later appeared that by combining streptomycin with other drugs, such as para-Aminosalicylic acid and Isoniazid, this resistance could be avoided in most instances. Our present chemotherapeutic program usually involves combinations of these drugs given for many months without significant interruption, in order to obtain the maximum benefit. Under chemotherapy, the following results may be observed. In far advanced tuberculous disease we often find bilateral tuberculous infiltrations extending through large areas of both lungs. During chemotherapy we usually observe rapid resolution of such infiltrations, so that all of the lesions may disappear from view except for a varying number of small residuals. As resolution occurs, linear strands of scar tissue may appear and remain as the only evidence of former disease. Other infiltrates may fail to clear completely, leaving residuals in the form of nodules or fairly well circumscribed lesions. These may persist or may show very slight clearing over many months. Such residual, nodular lesions may be considered for surgical removal, especially if there is any question of cavity or if, occasionally, the sputum should remain positive. During chemotherapy, the majority of cavities will close in six to eight months. They may gradually decrease in size and slowly fade out completely. Occasionally, they fail to change in size but the cavity wall is observed to thin out gradually, becoming almost of onion-skin thickness. When this happens, large cavities come to resemble emphysematous blebs. Still another type of cavity may at first become smaller, then fill with fluid, and later discharge its contents and reappear.