Objective: In view of the limitations of albumin in peritoneal dialysis (PD), we set out to evaluate whether total lymphocyte counts (TLC) could serve as a better prognostic indicator. We were also interested in how these parameters might differ between PD and hemodialysis (HD) patients. Design: In a retrospective study, we reviewed 113 charts from our dialysis unit. All laboratory analyses were performed by the Department of Clinical Pathology of the Nassau County Medical Center, using standard procedures. Intact parathyroid hormone (PTH) was sent out to Nichols Laboratories. Setting: All patients originated from the renal clinic at Nassau County Medical Center, a 612 bed public hospital. Patients: The 38 PD and 75 HD patients selected had been receiving dialysis for at least 12 months and up to 3 years. The PD patients received either continuous ambulatory and/or cycler PD. For the survivors, the averages of their routine chemical analyses were considered their representative values. For the nonsurvivors, the most recent laboratory values prior to their end point were considered. Main Outcome Measures: Mortality or apparent malnutrition leading to transfer to HD represented the end points for PD patients. Mortality alone was used as the end point for HD patients. Results: Within the PD population, serum albumin was not significantly lower in nonsurvivors compared to survivors, while the TLC was significantly lower in nonsurvivors (1277 ± 146/mm3 vs 2249 ± 236/mm3, p = 0.0036). The HD population demonstrated a significant difference in both TLC and serum albumin levels between its two prognostic groups; albumin was the better discriminator. Nonsurvivors had a 20% lower serum albumin than did the survivors (27.0 ± 1.6 g/L vs 34.0 ± 0.5 g/L, p = 0.0001). Patients on PD had a higher TLC than those on HD (p = 0.0001). Conclusions: In the HD population, but not in the PD population, both serum albumin and TLC were significantly higher in the group that survived. Serum albumin is a more powerful discriminator of mortality in the HD population, while TLC is a better discriminator of mortality in the PD population. For uncertain reasons, PD patients have a higher TLC than those on HD.