Purpose: The aim of this study was to elucidate the urodynamic features of patients with Y-type urethral duplication. Methods: Patients with Y-type urethral duplication were retrospectively analyzed. Clinical presentation, urodynamic findings, surgical methods, and treatment outcomes were reviewed. Results: From 2014 to 2016, six boys were diagnosed with Y-type urethral duplication at our institution. All patients underwent urodynamic testing. Urodynamic testing in patient 1 and 2 revealed detrusor pressure as 100 cmH2O and 88 cmH2O in the voiding stage, while urinary flow rate were 0 ml/s and 2.8 ml/s with volume of residual urine as 300 ml and 110 ml respectively, which consistent with the typical urodynamic of lower urinary tract obstruction. Patient 1, 3, 4 and 6 showed impaired bladder compliance as 7.5 ml/H2O, 12 ml/H2O, 6 ml/H2O and 6 ml/H2O respectively. Patient 5 and 6 also showed maximum urethral pressure as 110 cmH2O and 125 cmH2O with maximum urethral closure pressure as 103 cmH2O and 110 cmH2O respectively in the resting state. Conclusions: Y-type urethral duplication is one potential cause of lower urinary tract obstruction, as seen in the abnormal urodynamic findings in our patients. Further studies are needed to elucidate the characteristics of this rare condition and determine optimal surgical management. Type of study: Retrospective case series. (C) 2017 Elsevier Inc. All rights reserved.