Patients with clinically localized prostate cancer who might be cured by aggressive management are not easily identified using current clinical information. Additional, more accurate, biomarkers of tumor behavior need to be identified to improve clinical outcome. Our previous studies indicated that the concentration of the glycosaminoglycan chondroitin sulfate in prostatic stroma might be a useful biomarker of disease progression in early-stage prostate cancer. In this study, two chondroitin sulfate proteoglycans, versican and decorin, were investigated. Versican and decorin were immunolocalized to the periacinar and peritumoral fibromuscular stroma in sections of nonmalignant and malignant human prostate tissues. Video image measurements indicated that the concentrations of both proteoglycans were increased in the prostatic tissue of men with early-stage prostate cancer compared with tissue from men without cancer (P = 0.0006). Cox's univariate analysis indicated that increases in versican concentration but not in that of decorin were associated with increased risk of prostate-specific antigen (PSA) progression. Versican concentration was compared with other clinical or biological features of prognosis in two-variable regression analyses. Versican and serum PSA concentrations were independent predictors of PSA progression. Versican was a stronger prognostic factor than tumor grade, and it could predict outcome for patients with moderately differentiated tumors. Patients with low versican concentration had significantly better progression-free survival than patients with high levels of versican (Kaplan-Meier plot, 89% versus 27% PSA progression-free at 5 years, respectively; P = 0.0001). We conclude that the measurement of prostatic concentrations of versican, a molecule with reported anticellular adhesive properties, may be a useful marker of disease progression in patients with early-stage prostate cancer and that further study of versican in other patient cohorts is warranted.