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The development of an effective vaccine against the scbistosome is thought to be the most desirablemeans to control scbistosomiasis, even though there is an effective means of chemotherapy with praziquantel. A full-length cDNA encoding the Schistosoma japonicum proteasome subunit alpha type 5 protein(SjPSMAS) was first isolated from 78-day-scbistosomulum cDNAs. The cDNA had an open reading frame(ORF) of 747 by and encoded 248 amino acids. Real-time quantitative RT-PCR analysis revealed thatSjPSMAS is up-regulated in 78-day and 32-day scbistosomes, and the level of expression in male isaround fourfold higher than that in female worms at 42 days. The SjPSMAS was subcloned into pET28a(+)and expressed as inclusion bodies in Escherichia coli BL27 (DE3) cells. Western blotting showed that therecombinant SjPSMAS (rSjPSMAS) was immunogenic. After immunization of BALB/c mice with rSjPSMAS,reductions of 23.29％and 35.24%were obtained in the numbers of worms and eggs in the liver, respec-tively. The levels of specific IgG antibodies and CD4 cells were significantly higher (P<0.01)in the groupvaccinated with rSjPSMAS combined with Seppic 206 adjuvant than in the other groups, as detected byenzyme linked immunosorbent assay (ELISA) and flow cytometry. The study suggested that rSjPSMA5induced partial immunoprotection against S.japonicum in BALB/c mice, and it could be a potential vaccinecandidate against scbistosomiasis.