Endoscopic laser Doppler flowmetry (LDF) was used to study human bronchial microvascular perfusion in 25 healthy subjects. In total 617 recordings with good signal to noise ratio were obtained and, in the hands of an experienced bronchoscopist, the procedure did not cause major technical problems. Curve fluctuations synchronous to heart rate and respiration were identified. The spatial variation of measurements in one region was considerable, but when the mean of four measurements was used, acceptable precision levels were obtained. Regional differences were observed between 40.3 arbitrary perfusion units (PU) (34.0-46.6) in the right upper lobe bronchus and 77.3 PU (63.6-91.0) at the main carina. Measurements were obtained from the main carina, the right upper lobe bronchus, the apical segment of the right and left lower lobe bronchus. In all bronchi, recordings were performed at two locations distal to the bifurcation; 1-5 mm (central) and 6-10 mm (peripheral). The peripheral flux levels were significantly higher than the central (p < 0.001). Analysis of the short and long term temporal variation showed no significant differences, when the data was analyzed on a group basis. We conclude that LDF seems to be a promising method for future clinical investigations.