Objectives <p>The objective was to explore if adverse events during radical prostatectomy for prostate cancer were associated with oncological outcomes. A further objective was to identify risk factors for adverse events.</p> Methods <p>A post-hoc study nested in a prospective, controlled trial of radical prostatectomy by robot assisted laparoscopic or open retropubic approach in Sweden. Adverse events during surgery were collected from clinical record forms (CRFs) filled out by the surgeon at operation. Recurrence was identified from CRFs and patient reports, cause of death through the Swedish National Cause of Death Register. Recurrence was defined as undetectable PSA 6–12 weeks after prostatectomy followed by PSA &gt; 0.25 ng/ml or treatment for prostate cancer recurrence. Cox regression was used to explore associations between exposure and outcome.</p> Results <p>One/more adverse events occurred during 39% (1356/ 3444) of operations. Adverse events were associated with recurrence, but not with all-cause or prostate cancer specific mortality. Intraoperative extensive bleeding and difficulties during dissection were associated with recurrence. Risk factors included age at surgery, history of TUR-P or abdominal surgery, teaching, prostate weight and lymph node dissection. Limitations included the low number of observations (deaths), particularly in subgroup analyses and hospital volume. This study should be regarded as explorative.</p> Summary <p>In this explorative study adverse events during radical prostatectomy were associated with increased risk for recurrence.</p>