The expression of high-affinity IgE receptor (FcΕRI) on alveolar macrophages was examined in order to determine the association of alveolar macrophages with IgE-dependent inflammation. Immunostaining showed that a 15–1 monoclonal antibody against FcΕRI α chain reacted with alveolar macrophages from both atopic and non-atopic patients by immunostaining. In addition, preincubation of 15–1 monoclonal antibody specifically blocked monomeric IgE binding to alveolar macrophages. Reverse transcription polymerase chain reaction showed that CD14+ alveolar macrophages expressed FcΕRI α, β and γ chain mRNA. These results show that alveolar macrophages express FcΕRI and may participate in IgE-dependent inflammation mediated by FcΕRI.