29 adult patients with nasal polyps were studied. The clinical symptoms and atopic profile were compared with both the level of histamine and IgE found in polyp fluid. The high concentration of free histamine found in polyp fluid was probably pathological, and local IgE was present in greater amounts than expected by simple diffusion. There was no evidence that clinical hypersensitivity is associated with higher concentrations of IgE and histamine in polyp fluid; it is possible that mechanisms other than an IgE-mediated response could cause degranulation of mast cells in nasal polyps.