Ventilation and perfusion examinations using (133)Xe gas were done on 9 Patients with silicosis and 7 normal subjects. The data included single breath image (V-DOT), wash out image (WO) and perfusion image (Q-DOT) and were stored in a Shimadzu Scintipac 1200. The 9 patients were divided into two types according to the classification by chest X-ray findings of the Japanese Labour Ministry, namely type I (3pts) and type II (6pts). Six regions of interest (ROI) were established: the upper, middle and lower lung fields of both lungs. There were no statistically significant differences in the V-DOT/Q-DOT of the six ROI between patients with silicosis and the normal control subjects. However, there were statistically significant differences in the MTT of the right upper and middle lung fields between the 6 patients with type II silicosis and the normal control subjects. This study showed that obstructive changes in the early stage of silicosis start from the upper lung field.