Human adenoids and tonsils were disintegrated mechanically and the cells dispersed by passage through a stainless-steel screen in EDTA-containing buffer. Collagenase digestion did not increase the yield of adenoidal cells. The mast cell content of the cell suspensions was in the range of 1-10 mast cells/10(4) cells with an estimated mean of 1-2 mast cells/10(4) cells, a value considerably below previous reports on adenoidal cell suspensions. The mast cell content was determined by staining with toluidine blue at low pH (to prevent interference by phagocytes). The mast cell count as assessed by alcian blue staining and by fluorescence microscopy after FITC-anti-human IgE binding was similar. Various attempts to enrich the cell suspension (i.e. by differential centrifugation, by gradient centrifugation on Ficoll or Ficoll-Hypaque and by velocity sedimentation at unit gravity) all gave negative results.