['Previous studies have reported p-cresyl sulfate (PCS) was related to endothelial dysfunction and adverse clinical effect. We investigate the adverse effects of PCS on clinical outcomes in a chronic kidney disease (CKD) cohort study.', '72 predialysis patients were enrolled from a single medical center. Serum biochemistry data and PCS were measured. The clinical outcomes including cardiovascular event, all-cause mortality, and dialysis event were recorded during a 3-year follow-up.', 'After adjusting other independent variables, multivariate Cox regression analysis showed age (HR: 1.12, P = 0.01), cardiovascular disease history (HR: 6.28, P = 0.02), and PCS (HR: 1.12, P = 0.02) were independently associated with cardiovascular event; age (HR: 0.91, P < 0.01), serum albumin (HR: 0.03, P < 0.01), and PCS level (HR: 1.17, P < 0.01) reached significant correlation with dialysis event. Kaplan-Meier analysis revealed that patients with higher serum p-cresyl sulfate (>6\u2009mg/L) were significantly associated with cardiovascular and dialysis event (log rank P = 0.03, log rank P < 0.01, resp.).'] Is p-cresyl sulfate a valuable predictor of clinical outcomes in pre-ESRD patients?