Objective To observe the expression of inhibitor of Zeste 12(SUZ12) and matrix metalloproteinase-9(MMP-9) in retinoblastoma(RB) and their significance .Methods The paraffin embedded specimens from 56 patients with RB were studied ,10 patients belong to intraocular stage ,28 patients intraocular pressure increased stage and 18 patients outside ocular stage among them .22 ,16 ,12 ,and 6 patients with invasion degree(N) from N0-N3 differently ,while10 ,16 ,18 and 12 patients with cell differenti-ations(D) from D0-D3 differently .The expressions of SUZ12 and MMP-9 protein in 56 patient s were detected in different clinical stages ,invasion degree and cell differentiation by immunohistochemical staining and their correlations were analyzed .Results The expressions of SUZ12 and MMP-9 in RB tissues[(31 .48 ± 12 .20)% ,(34 .49 ± 13 .25)% ]were obviously higher than in para-cancer tissue[(0 .26% ± 0 .06)% ,(0 .36 ± 0 .08)% ](P<0 .01) .The expression of SUZ12 was related to clinical stages ,invasion degree and cell differentiation .The expression of SUZ12 and MMP-9 in intraocular pressure increased stage was obviously higher than in-traocular stage(t=10 .299 ,16 .253 ;P<0 .01) ,and outside ocular stage was obviously higher than intraocular stage (t= 20 .819 , 36 .417 ;P<0 .01)and intraocular pressure increased stage (t= 10 .348 ,15 .061 ;P< 0 .01) .The expression of SUZ12 and MMP-9 was increasing from N0 to N3 but decreasing from D0 to D3 .The expression of SUZ12 in RB was related to MMP-9 expression(r=0 .840 ,P=0 .000) .Conclusion The expression of SUZ12 and MMP-9 increased in RB tissue and it is helpful to predict the malig-nancy degree of RB .