Objective: To determine if patient size or weight at the start of PD influences patient or technique survival. Design: A prospective cohort study of adult PD patients. Setting: A university and a Veterans Administration outpatient dialysis unit. Patients: 343 adults patients with 660 years on PD enrolled from 1979 to 1995. Main Outcome Measures: Patient survival (censoring for transplant, 60 days post-transfer to hemodialysis, and end of study)and technique survival (censoring for death, transplant, or end of the study) for patients as grouped by weight (less than or equal to 64 kg vs. >64 kg or less than or equal to 82.7 kg vs. >82.7 kg) or BSA (less than or equal to 2.0 m(2) vs >2.0 m(2)). Results: Patient survival was 86.3% at one year, 77.0% at two years, 65.2% at three years, and 56.9% at 4 years. Technique survival was 84.9% at one year, 77.5% at two years, 63.5% at three years, and 58.3% at four years. The patient and technique survival curves were not significantly different for patients as grouped by weight or BSA. Using Cox proportional hazards model, age, diabetes, peritonitis rate, and albumin at the start of PD were independent predictors of patient survival, but BSA and weight were not. The only predictor of technique survival was the peritonitis rate. Larger patients had higher initial albumins, which may indicate better nutritional status that may offset the risk of underdialysis. Conclusions: Large patients do as well as smaller patients on PD. Size alone should not preclude patients from PD.