Nasal mucus clearance (N.M.C.) varies with geographical conditions. Studies on the evaluation of this important function have so far been done only in the western part of the world, but now the normal values of N.M.C. in India have been established by measuring the transportation of saccharine crystals through the nose. This has been compared with the values obtained in various diseases of the nasal and lower respiratory tracts, thus establishing the prognostic and diagnostic importance of measuring the nasal mucus clearance.