Objective: To study the prevalence and risk factors for malnutrition in a peritoneal dialysis (PD) center with an active PD program. Methods: We assessed the nutritional status in 205 continuous ambulatory peritoneal dialysis (CAPD) patients, including stable and unstable patients, by subjective global assessment (SGA), dietary diaries and biochemistry index. Serum C-reactive protein (CRP) levels were examined as inflammatory marker. Fluid status including extracellular water (ECW), intracellular water, and total body water (TBW) was evaluated by multiple-frequency bioelectrical impedance analysis and brachial blood pressure was measured. New comorbidities included systemic infection, congestive heart failure and trauma that occurred within 1 month or less. Cardiovascular disease (CVD) was recorded too. Dialysis adequacy and residual renal function were calculated by a standard technique. Results: Based on SGA, 15.6% of our CAPD patients were malnourished. The malnourished patients had advanced age, higher CRP and ECW/TBW levels than normally nourished patients (age: 68.78 ± 11.92 vs. 59.26 ± 13.46 years, p = 0.001; CRP: 11.98 ± 20.22 vs. 5.56 ± 8.30 mg/l, p = 0.004; ECW/TBW: 0.55 ± 0.16 vs. 0.52 ± 0.04, p = 0.049). Patients with malnutrition were more prone to have CVD (53.13 vs. 31.79%, p = 0.004) and new comorbidities (65.62 vs. 4.62%, p = 0.023). Multivariate analysis showed new comorbidities, mostly systemic infection, which were associated with nutritional status (p < 0.001). Both ECW/TBW and new comorbidities were associated with serum CRP, CVD and malnutrition (p < 0.001–0.05). In contrast, some traditional factors which were recognized as contributing to malnutrition such as residual renal function, dialysis adequacy, metabolic acidosis, total protein loss, diabetes and Charlson indexes were not different between normally nourished and malnourished patients in the present study. Conclusions: Our results suggest that only 15.6% of patients were malnourished in our PD program. Old age, inflammation, CVD, fluid overload and new comorbidities were all associated with malnutrition, with new comorbidities, mostly systemic infections, being the most significant risk factor. However, many traditional factors such as residual renal function, dialysis adequacy and diabetes were not.