ABSTRACT Purpose: In this study the frequency and outcomes of unintentional testicular artery ligation during microsurgical varicocelectomy were evaluated. Materials and Methods: From 1984 to 2002, 2,102 cases of microsurgical varicocelectomy were evaluated. Accidental artery ligation was confirmed intraoperatively by observation of pulsatile twitching of the ligated vessel stump under 25× magnification. Results: The complication was identified in 19 cases (0.9%) and all occurrences were unilateral, with 74% on the left side and 42% on the right side. In addition to the vasal artery at least 1 alternative artery was identified in all cases. Average testis volume before surgery was 15.8 ml. Azoospermia was found in 26% of cases. After surgery during the median followup of 19 months testicular atrophy developed in 1 patient (5%). In this cohort significant improvement was found in serum total testosterone in 80% (from 362 to 493 ng/dl) and in sperm count in 80% (from 12 to 22 × 10 6 per ml). Return of motile sperm to the ejaculate was found in 40% of azoospermic cases. The natural pregnancy rate was 14%, which is significantly lower than the 46% previously reported in the historical cohort of varicocelectomy cases. Conclusions: The incidence of accidental testicular artery ligation in microsurgical varicocelectomy was approximately 1%. Testicular atrophy developed in 1 patient (5%). Preservation of cremasteric and/or secondary internal spermatic arteries likely contributed to a low incidence of adverse outcomes. The natural pregnancy rate was low which may be due to the high proportion of azoospermic men before surgery. It is possible that the smaller testes usually associated with azoospermia indicate smaller testicular arteries, thus posing a greater risk of accidental ligation.