Objective To investigate the expression and significance of IDO and c-myc in bladder urothelial carcinoma.Methods IDO mRNA expression from fresh tumor and mucosa specimens from 20 cases were detected by fluorescence quantitative PCR,and SP was used to detect the IDO,c-myc protein in paraffin-embeded specimens from 84 cases and mucosa specimens from 22 cases.Results In bladder urothelial carcinoma,IDO,c-myc protein expression level had no relationship with age and sex.Expression of IDO protein in invasive bladder urothelial carcinoma was significantly higher than that of no-invasive (x2 =5.600,P =0.018).With the increase of the histological grade (x2 =20.268,P =0.000) and UICC stage (x2 =12.075,P =0.007),the positive expression rate of IDO protein was increased.There was not positive expression of c-myc protein in normal bladder tissue,but in bladder urothelial carcinoma,44 cases (52.4 ％) were positive expression (x2 =10.733,P =0.001).The expression of c-myc protein had no relationship with the histological classification,histological grade and UICC stage.In bladder urothelial carcinoma tissue,IDO protein expression level was positively correlated with c-myc protein expression (r =0.205,P =0.047),and was positively correlated with the histological classification,histological grade and UICC stage (r =0.258,P =0.018; r =0.491,P =0.000; r =0.365,P =0.001).Expression of IDO mRNA in bladder urothelial carcinoma (7.696 1±1.745 2) was significantly higher than that in normal bladder tissue (6.397 0±1.205 1)(t =2.367,P =0.023).The average expression level of IDO mRNA in bladder urothelial carcinoma of Ta-T1 stage was 6.803 4±1.567 5,which was significantly lower than that in T2-T4 stage (9.183 8±0.690 3) (t =4.955,P =0.000).The average expression levels of IDO mRNA in grade Ⅰ,Ⅱ,Ⅲ bladder urothelial carcinoma were 7.058 7±1.771 5,7.934 2±1.530 5,9.290 7±0.574 5,respectively,which were increased with the grade increasing (t =2.729,P =0.011).Conclusions The high expression of IDO correlates with bladder urothelial carcinoma progression,and expression of c-myc is irrelevant with bladder urothelial carcinoma progression,but maybe associate with bladder urothelial carcinoma occurrence.IDO may be a predictive factor of prognosis.IDO and c-myc may be therapeutic target in the treatment of bladder urothelial cancer.