In 45 patients with different pulmonary diseases and diverse impairment of pulmonary function, their pulmonary function was evaluated with radiography, spirometry, diffusion capacity, differential spirometry, and pulmonary gammagraphy (lung scanning). Percent comparisons were made between the data obtained from the differential spirometry about ventilation and perfusion, and an estimate of ventilation from the chest radiograph and the results from pulmonary gammagraphy. Because the correlation coefficient between the above mentioned data were high, evaluation of function from pulmonary radiography and gammagraphy can be used to study the function of each lung at rest ‘in lieu’ of different spirometry.