Eight immunological methods all using the same monoclonal antibody reagent were compared for the detection of Trichinella spiralis antigen. These were based on: (1) the direct adsorption of the antigen to the immunoadsorbent (nitrocellulose membrane, polyvinyl chloride strip or microplate); (2) capture of the antigen by antibodies pre-sensitized on the immunoadsorbent; and (3) latex agglutination. The methods found suitable were: (a) capture radioimmunoassay (capture-RIA) (sensitivity: less than 0.5 microgram/ml antigen); (b) direct enzyme immunoassay (direct-ELISA) (less than 0.5 microgram/ml); (c) tube latex agglutination test (2.2 micrograms/ml); and (d) direct immunodot assay (8.8 micrograms/ml). However, the performance of the direct-ELISA was greatly affected by the presence of each of three extraneous substances (bovine serum albumin (BSA), lipopolysaccharide (LPS), normal swine muscle homogenate (NSM) added to the antigen sample. The direct immunodot assay was also affected by the presence of BSA or LPS, whereas both the capture-RIA and the tube latex agglutination methods were affected by the presence of NSM only. The findings are discussed with a view of detecting T. spiralis larvae directly from pork samples by immunological means.