Data from a phase III trial demonstrate that zinc-α 2-glycoprotein (AZGP1) status at radical prostatectomy is predictive of outcomes of patients with prostate cancer, after a median follow-up duration of 15.8 years. Biopsy samples from a total of 347 patients undergoing radical prostatectomy were analysed using immunohistochemistry. Low or absent AZGP1 expression was found to be an independent predictor of a short biochemical-relapse-free survival duration, relative to mean levels of AZGP1 and also improved the discriminatory value of existing prognostic risk models. These findings indicate the clinical merit of AZGP1 expression as a prognostic biomarker in men with prostate cancer.