Eosinophil infiltrations were observed in the intestine and the muscle of both Trichinella spiralis-infected (WBxC57BL/6)F1-W/Wv mice and their littermates, WBB6F1−+/+, +/W, +/Wv, almost to the same extent. W/Wv mice did not show infiltration of subepithelial mast cells and globule leucocytes in response to T. spiralis infection. Increased numbers of these cells were observed in their littermates. Worms in W/Wv mice were retained for longer periods than those in littermates. Also, no difference was noted in the production of specific serum antibodies between W/Wv mice and their littermates, as determined by passive cutaneous anaphylaxis (PCA) for specific IgE and by indirect haemagglutination (IHA). These results suggest a possible participation of SMC, GL and eosinophils in the expulsion of adult T. spiralis.