【Objective】To evaluate F(ab′)2 f ragment of monoclonal antibody C50 using radio immunoscintig raphy(RIS)for ovarian carcinoma ..【Methods】C50 w as digested by pepsin and identified w ith SDS-PAGE . Af ter purified by Sephadex G-100

C50 、F(ab′)2

and normal mouse IgG(nMIgG)were labeled w ith 9　9mTc and injected introperitoneally into 3 groups of nude mice bearing human ovarian carcinoma xenog raf ts respectively . Af ter 24 hours

RIS w as performed .【Result】①The recovery of F(ab′)2 af ter digestion and purification w as 33 %±3.2 %

about 49 % of the maximal theo retical yield .Good immunoactivi ty of F(ab′)2 w as retained and tested by ELISA and PAP .②Higher radioactivity g athered in xenog raf ts field in fragment g roup

and T/N T is the hightest one among three groups .【Conclusio n】F(ab′)2 f ragment could be of better RIS than intact monoclonal antibody .