SummaryThe antigenic components of aParagonimus heterairemussaline extract were revealed by SDS‐PAGE and Western blot analysis using sera from 32 patients withP. heterotremusinfection. 60 with other helminthiasis, and 15 normal human sera. It was found that the worm extract was comprised of more than 13 polypeptides. among which 5 components were strongly recognized by paragonimiasis sera. These components had approximately showed molecular weight of<12‐3. 12 3, 18‐5, 31,‐5 and 38 kD. Only the 31.5 kD component was recognized by all 32 paragonimiasis sera. Sera from other helminth infections and from uninfected did not produced detectable bands with the worm extract. The present findings suggested that the 31.5 kD component may be sensitive and specific for the diagnosis of human paragonimiasis heier