In order to identify early specific diagnostic antigens of Spirometra erinaceieuropaei (syn. S. erinacei or S. mansoni) sparganum, soluble proteins were analyzed by two-dimensional electrophoresis (2-DE) and western blotting probed with immune sera from infected mice at 14 days post-infection. From a total of approximately 462 proteins spots mainly distributed in pI range of 5-6.6 and with molecular mass of 25-48 kDa, 6 immuno-reactive protein spots with molecular mass of 31.8-38.3 kDa were characterized by MALDI-TOF/TOF-MS. Three proteins were identified as S. erinaceieuropaei cysteine protease, Toxoplasma gondii hypothetical protein and Pecten spp actin, while the remaining were unidentified. The cysteine protease from S. erinaceieuropaei soluble proteins recognized by early infection sera might be developed as diagnostic reagent for early detection of sparganosis.