Objectives: Testosterone has an important role in the development of the urethra. The present study aimed to evaluate the impact of testosterone levels on the severity of urethral stricture disease (USD) and the outcome of its treatment. 
Methods: This is a prospective study that included adult patients with primary USD who were scheduled for urethroplasty. The serum testosterone (free and total) levels were assessed on the morning of the operation day. At 1 month postoperatively we assessed the International Prostatic Symptoms Score (IPSS), maximum flow rate (Q-max) and post-voiding residual volume (PVR).
 Results: This study included 70 patients. Preoperative total testosterone levels ranged from 212 to 1093.7 ng/dL, and the serum free testosterone ranged from 3.54 to 12.9 ng/dL. Nineteen patients (27.1%) had low testosterone. The serum testosterone levels showed a statistically significant negative correlation with the patient's age, BMI, and preoperative post-voiding residual volume (PVR) and a significant positive correlation with Q-max levels. The overall surgery success rate was 90%. The predictors for procedure failure were the presence of DM (p=0.039; OR: 0.179, 95% CI: 0.035-0.92), the levels of PVR (p=0.002; OR: 1.013, 95% CI: 1.005-1.021), and serum total testosterone levels (p=0.026; OR: 0.996, 95% CI: 0.993-1). However; serum testosterone levels failed to show significant association with the surgery outcome or the postoperative complications in the multivariate regression analysis
 Conclusion: The present study supports the impact of low testosterone levels on the severity of USD. However, its impact on the surgery outcome is still questionable.