Abstract Objective: To report the sensitivity and specificity of neural precursor cell-expressed developmentally down-regulated protein 9 (NEDD9) protein high expression in predicting BCG response and its effect on recurrence or progression free survivals. Patients and methods: Between May 2014 and April 2017, a prospective cohort study was conducted on 105 patients with intermediate or high-risk nonmuscle invasive bladder cancer. Immunohistochemical staining with mouse monoclonal anti-NEDD9 antibody was done. Examination of the slides was done to detect NEDD9 cytoplasmic expression. Intravesical induction bacillus Calmette-Guerin (BCG) instillation therapy was started for all patients 2 to 4 weeks after endoscopy with once weekly instillation for 6 weeks. Intravesical maintenance BCG instillation was then continued every 3 months for at least 1 year. Follow up with cystoscopy every 3 months for 2 years and every 6 months after that. Results: The mean age ± SD of the patients was 57 ± 4.5 years. The median follow-up period was 25 (12–36) months. NEDD9 protein was highly expressed in 61 (58.1%) patients, whereas low expression was in 44 (41.9%) patients. Sensitivity and specificity of NEDD9 high expression in predicting recurrence were 83.6% and 64.2%, respectively. Its sensitivity and specificity in predicting progression to muscle invasion or distant metastases were 91.3% and 51.2%, respectively. Its sensitivity and specificity in predicting complete response to BCG therapy were 84.1% and 80.9%. Kaplan-Meier test showed highly significant difference (P o 0.0001) in survival without recurrence or progression between patients showing high expression and those showing low expression. Conclusion: NEDD9 protein tissue marker could be used as a predictive marker for BCG response in nonmuscle invasive bladder cancer with reasonable sensitivity and specificity. r 2018 Elsevier Inc. All rights reserved