['We tested whether the addition of preoperative circulating plasminogen activator inhibitor type I levels improves the accuracy of standard preoperative and postoperative models for prediction of biochemical recurrence after radical prostatectomy.', 'Preoperative plasma levels of plasminogen activator inhibitor type I were measured in 429 consecutive patients treated with radical prostatectomy for clinically localized prostate cancer. The patients were randomly divided into a development (67%, 286) and a split sample validation cohort (33%, 143). Cox regression analysis was used to develop prognostic nomograms for prediction of biochemical recurrence.', 'In standard univariate analyses categorically coded preoperative plasminogen activator inhibitor type I was significantly associated with biochemical recurrence (p <0.001). In standard preoperative and postoperative multivariate analyses preoperative plasminogen activator inhibitor type I was independently associated with biochemical recurrence (p <0.001 and p = 0.002, respectively). In the split sample validation cohort the addition of plasminogen activator inhibitor type I increased the predictive accuracy of the preoperative multivariate model by 1.2%, 7.7%, 10.3%, 6.7% and 5.4% at 1, 2, 3, 4 and 5 years, respectively (p values <0.001). Moreover, the addition of plasminogen activator inhibitor type I increased the predictive accuracy of the postoperative model by 0.5%, 1.1%, 4.0%, 2.4% and 3.6% at 1, 2, 3, 4 and 5 years, respectively (p values <0.001).'] Does plasminogen activation inhibitor-1 improve the predictive accuracy of prostate cancer nomograms?