Hospitalization rates are declining more rapidly for peritoneal dialysis (PD) than for hemodialysis patients. This has been postulated to be caused in part by lower peritonitis rates. However, the causes of admission have not been reexamined in the setting of declining rates. We prospectively examined our hospitalization rates, causes of admission, and impact of peritonitis on hospitalization in adult PD patients at a single center over a 4-year period. There were 274 admissions in 168 patient-years for a rate of 1.6 admissions and 13.0 hospital days per patient-year. Rates were greater for men (1.8 v 1.5; P = 0.013), patients with diabetes (2.2 v 1.4, P < 0.001), and those with a higher peritoneal equilibration test result. Creatinine clearance and sex were independent predictors in a multivariate analysis. The most common causes for admission were cardiac disease (14.6%) and peritonitis (13.5%). Peritonitis accounted for 0.21 admissions and 2.0 hospital days per patient-year. Thirty percent of the incident patients were admitted during the first 90 days of dialysis. Admissions for dehydration and glucose abnormalities were more common in the first 90 days. Overall admission rates, as well as admission rates for peritonitis, did not change over time, although hospital days per year decreased. Those admitted for peritonitis had higher peritonitis rates, more time on PD, and were more likely to be black. Eighty-one percent of the admissions for peritonitis were caused by Staphylococcus aureus, Streptococcus spp, or gram-negative/fungal peritonitis. Patients with peritonitis caused by Staphylococcus epidermidis were less likely to be admitted than patients with peritonitis caused by other organisms. To conclude, peritonitis remains a common cause of hospitalization, despite low peritonitis rates. To decrease admissions for peritonitis, attention should be focused on preventing peritonitis caused by organisms other than S epidermidis.