We determined whether neutrophil infiltration into the stomach wall occurred during systemic anaphylaxis in mice and assessed the participation of mast cells in the response. Normal mice sensitized and challenged with antigen exhibited significant neutrophil infiltration in the gastric mucosa and submucosa compared with saline-challenged mice. The development of clinical signs of anaphylaxis and extent of gastric neutrophil infiltration was similar in mast cell-deficient Kit(W)/Kit(W-v) or Mgf(Sl)/Mgf(Sl-d) mice and the respective normal congenic mice. Pretreatment with sodium cromoglycate prevented the clinical signs of anaphylaxis and significantly diminished the infiltration of neutrophils in +/+ or Kit(W)/Kit(W-v) mice. Systemic anaphylaxis is associated with neutrophil infiltration into the stomach wall in mice, and mast cells are not required for the development of either the clinical manifestations or gastric neutrophil infiltration observed in the response.