A redistribution of mast cells towards the epithelial lining of the nasal mucous membrane has been shown to be a part of the allergic inflammatory reaction in hay fever. This results in an increased number of metachromatically stained cells on the surface of the mucous membrane. The involvement of mast cells in other inflammatory reactions in the human nose is not clarified and this may partly be due to methodological difficulties. Utilizing a recently developed imprint technique, specimens were taken from patients with infectious rhinosinusitis in acute and chronic stages. The total number of mast cells on 2 cm2 of the imprint area were counted. Mast cells in extremely low numbers were found in 5 out of 26 patients. Our results indicate that mast cell migration is not present in patients with infectious inflammatory reactions of the nasal mucous membrane.