BACKGROUND The malnutrition-inflammation score (MIS) is an indicator of malnutrition-inflammation complex syndrome and an outcome-predictor in maintenance hemodialysis (MHD) patients. However, its utility in peritoneal dialysis (PD) patients and its association with the Charlson comorbidity index (CCI) have not yet been examined. METHODS All chronic stable PD outpatients in the PD center of National Taiwan University Hospital in January 2006 were studied and followed for up to 18 months. The baseline MIS and CCI at the beginning of the study and the dates and causes of mortality or hospitalization during the study period were obtained. RESULTS A total of 141 PD patients were enrolled. During the study period, 8 patients died and 40 patients had major cardiovascular or infection events. The CCI correlated positively and significantly with the MIS (r = +0.344, p < 0.001). The MIS and CCI were both independent predictors of cardiovascular and infection events in the multivariate Cox proportional hazard model. For every one unit increase in the MIS, the adjusted hazard ratio for mortality was 1.177 (95% CI 1.050-1.320, p = 0.005). For every one unit increase in the CCI, the adjusted hazard ratio for mortality was 1.180 (95% CI 1.046-1.330, p = 0.007). CONCLUSIONS MIS can predict fatal and nonfatal cardiovascular and infection events in chronic stable PD patients. The CCI, which is closely associated with the MIS, is an independent determinant of cardiovascular and infection events as well. Interventional studies are indicated to confirm the utility of the MIS in PD populations who undergo nutritional or anti-inflammatory treatments.