Spinability of normal mucus and of sputum collected in chronic bronchitic patients was measured using an automatic device derived from that developed by CHRETIEN et al (1977) for cervical mucus. Spinability of sputum decreased as the purulence increased. Although significant correlations were found between spinability and apparent viscosity (r = - 0.50, p less than 0.05) or elasticity (r = 0.54, p less than 0.02), large variations in spinability were observed for sputum samples ranging in a zone of low viscosity and elasticity. Sputum with high spinability exhibited normal transport rate on the depleted frog palate although their viscosity and elasticity were abnormally low. The significant correlation obtained between spinability and sputum transport rate (r = 0.61, p less than 0.01) suggests that this rheological factor, along with viscosity and elasticity, plays an important role in the mucociliary transport mechanism.