Total IgE, specific IgE and histamine in sera from 35 documented cases of cysticercosis and 30 transfusion donors were measured and mast cell degranulation test was performed. Total IgE levels (730.61 U/ml), the positive rate of specific IgE (85.7%), histamine levels (5.3 micrograms/ml) and the positive rate of mast cell degranulation (42.9%) of the patients were found to be significantly higher than those of the normal group (P less than 0.01). The results suggested that the antigen of Cysticercus cellulosae could induce IgE production and mast cell degranulation, resulting in the release of histamine. It was, therefore, deemed that the IgE and IgE-mediated immunoreaction might be involved in the pathogenesis of human cysticercosis.