Background: To retrospectively identify the individual risk factors for the urethrocutaneous fistula (UCF) in pediatric patients after hypospadias repair (HR) with onlay island flap urethroplasty. Methods: A total of 167 patients who underwent primary HR at Nanjing Medical University Affiliated Children Hospital from January 2009 to December 2012 were enrolled. Clinical data including the patient' age at HR, hypospadias type and urethral defect length were documented. Results: Among 167 patients, 12.6% patients (n = 21) developed UCF after HR. Postoperative UCF occurred in 3.9% (3/76) cases at age of 0-2 years, 14.3% (9/63) at 2-4 years, 20.0% (2/10) at 4-6 years and 38.9% (7/18) at 6-12 years. The incidences of UCF were 12.0% (3/25), 11.4% (5/132) and 30.0% (3/10) for distal, middle and proximal types of hypospadias. As to the urethral defect length, the incidences of UCF were 8.2% (5/61) in patients with a length of = 2 cm, 12.8% (9/70) in 2-3 cm, 22.6% (7/31) in 3-4 cm and 0% (0/5) in above 4 cm. Older age at HR was significantly associated with the high incidence of UCF formation (P = 0.004), while the hypospadias type and urethral defect length did not affect it (P = 0.264 and P = 0.312, respectively). Conclusions: The patient' age at HR was a risk factor for the UCF formation after HR, and treatment of HR within two years old might be with the least incidence of UCF.