Aim: Residual renal functions have positive effects on morbidity and mortality among patients undergoing peritoneal dialysis. Our aim is to investigate the effects of baseline laboratory data and longitudinal uric acid and C-reactive protein (CRP) levels on loss of residual renal functions within the first three years of peritoneal dialysis. Materials and Methods: This is a retrospective cohort study. Thirty-four patients who started peritoneal dialysis due to end-stage renal disease were included. The primary endpoint was loss of residual renal function and was defined as residual urine volume of less than 200 mL/24 hours. Patients were followed for three years after the onset of peritoneal dialysis or until loss of residual renal functions. Demographic and clinical data were recorded retrospectively. Results: The follow-up period was 32.7 (12.9-36) months. Ten patients lost residual renal function 22.1±9.8 months after the initiation of peritoneal dialysis. Longitudinal uric acid level was 6.1±1.2 mg/dL and longitudinal CRP level was 0.5 (0.3-0.7) mg/dL. In patients with residual renal function loss, baseline sodium and triglyceride were lower, while parathormone were higher. There was no difference between the groups in terms of longitudinal uric acid and CRP levels. Baseline parathyroid hormone [hazard ratio (HR), 1,003; 95% confidence interval (CI) 1,001-1,006; p=0.013], body mass index (HR 0.817; 95% CI 0.684-0.975; p=0.025), and baseline sodium level (HR 0.801; 95% CI; 0.665- 0.965; p=0.019) were risk factors for residual renal function loss. Conclusion: In peritoneal dialysis patients, residual renal function loss were associated with baseline sodium, triglyceride, and body mass index. There was no correlation between residual renal function loss and longitudinal CRP and uric acid levels. Prospective studies are needed to determine the optimal uric acid and CRP levels.