PURPOSE We evaluated sperm DNA fragmentation in patients with vasectomy reversal and its prognostic value to determine spontaneous and assisted reproductive technique pregnancy rates. MATERIALS AND METHODS We prospectively assessed DNA fragmentation with the sperm chromatin structure assay in postoperative semen samples of 70 patients with vasectomy reversal. At a median +/- SD followup of 4.3 +/- 0.5 years pregnancy rates were recorded. RESULTS DNA fragmentation in patients with vasectomy reversal was significantly increased vs that in proven fertile controls (30.2% +/- 20.1% vs 15.3% +/- 5.4%, p <0.001). Significant negative correlations were found between DNA fragmentation index and total sperm count, progressive motility, total number of progressive sperm, normal morphology and sperm vitality (-0.325 <r <-0.805). The obstructive interval did not correlate with DNA fragmentation. The spontaneous pregnancy rate was 46%. Significantly higher log total progressive sperm motility (p = 0.021) and a trend toward lower female age (p = 0.064) were detected in the spontaneous vs the no pregnancy group. No association was found between DNA fragmentation and the pregnancy rate. CONCLUSIONS Increased DNA fragmentation is present in semen samples of men after vasectomy reversal vs fertile controls but DNA fragmentation is not associated with spontaneous or assisted reproductive technique pregnancy rates in these patients.