A multidetector system for regional pulmonary function evaluations using xenon-l33 is described. Sixteen KaI(T1) detectors (eight collinear pairs) are employed and counting data is accumulated into a 1600-word magnetic core memory via a high speed, buffered, data acquisition system. The data are read out from the magnetic core memory to digital magnetic tape for processing and analysis using a laboratory computer system.A general description of the experimental techniques of radiospirometry and of the methods for data analysis is given.