Preliminary results from the relationship between aging and mucociliary clearance of inhaled 99-Tc human albumin particles (0.92-2.5 microns) are reported from two groups of healthy non-smokers: 1) 20-61-year-old (mean 42 years) and 2) 71-90-year-old (mean 79.5 years). The analytical procedure is presented, and on the basis of the analysis it is concluded that there is evidence for an age-related decline of the mucociliary clearance by a bi-phasic curve, similar to those reported in the literature for other physiological functions.