Ten healthy male cardiopulmonary technicians, 10 aircrew members, and 10 patients performed a series of pulmonary function studies to compare the Cavitron Spirometric Computer to the conventional water-sealed Collins 13.5-/spirometer. A total of 50 studies were performed on the spirometers individually and then with the spirometers linked in-line. The Cavitron FVC averaged 6% less, the FEV1--7% less, and the FEF 25-75%--11.6% less than comparable measurements from the Collins spirometer. Since these difference are within the suggested guidelines for screening studies, the Cavitron Spirometric Computer is acceptable for use in clinical screening spirometry.