Background/Aims. 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.Methods. 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.Results. 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 mg/L) were significantly associated with cardiovascular and dialysis event (log rankP=0.03, log rankP<0.01, resp.).Conclusion. Our study shows serum PCS could be a valuable marker in predicting cardiovascular event and renal function progression in CKD patients without dialysis.