Objective: To assess value of immediate postoperative intravesical instillation of pirarubicin after transurethral resection (TURBT)of non-muscle invasive bladder cancer. Methods: 484 patients diagnosed with non-muscle-invasive bladder cancer admitted to the Second Affiliated Hospital of Kunming Medical University were divided into two groups after transurethral resection of bladder tumor. 285 patients received postoperative intravesical instillation of pirarubicin within 6 hours after the surgery, 199 patients received first instillation of pirarubicin at 10 days after the surgery, after that, all the patients received routine bladder perfusion chemotherapy. Patients who received intravesical instillation of pirarubicin within 6 hours were defined as immediate intravesical instillation group and the other patients as the control group. Based on the European Organisation for Research and Treatment of Cancer risk tables, scores of recurrence and progression of patients were calculated and then stratified into risk groups accordingly. Recurrence and progression rates of the immediate intravesical instillation group were analyzed and then compared with the corresponding reference of the risk tables. Results: The 1-year and 5-year recurrence rate of patients with EORTC table scoring 0 in the immediate intravesical instillation group were significantly lower than that of the EORTC reference group (5.3% and 14.0% vs 15.0% and 31.0%, P<0.05). 1-year recurrence free rate between the immediate intravesical instillation group and the control group in patients scoring 1-4 was significantly different (81.3% vs 76.7%, P=0.014). However, 1-year recurrence free rate of the immediate intravesical instillation group was comparable with that of the control group in patients scoring 5-9, 10-17(P>0.05), which is quite close to the EORTC reference. The probability rates of 1-year and 5-year progression of the 285 patients who received immediate intravesical instillation group did not show significant difference with the EORTC reference. On multivariate analysis, previous recurrence, tumor grade G2-3, tumor multiplicity, delay of immediate intravesical instillation were independent risk factors of recurrence(P<0.05). Conclusions: With the help of EORTC recurrence risk table stratifying the patients into different risk groups, our study showed that delay of immediate postoperative intravesical instillation of chemotherapy after TURBT was an independent risk factor of post-surgery recurrence of tumor. Moreover, patients with EORTC scoring 1-4 might obtain greatest benefits.