Background: The causes, predictors, treatment, and outcomes of relapsed and recurrent peritoneal dialysis (PD)-associated peritonitis are poorly understood. Study Design: Observational cohort study using Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry data. Setting & Participants: All Australian PD patients between October 1, 2003, and December 31, 2007, with first episodes of peritonitis. Predictors: Demographic, clinical, and facility variables and type of peritonitis; relapse (same organism or culture-negative episode occurring within 4 weeks of completion of therapy of a prior episode or 5 weeks if vancomycin used); recurrence (different organism occurring within 4 weeks of completion of therapy of a prior episode or 5 weeks if vancomycin used); control (first peritonitis episode without relapse or recurrence). Outcomes & Measurements: Hospitalization, catheter removal, hemodialysis therapy transfer, death. Results: Of 6,024 PD patients studied, first episodes of relapsed, recurrent, and control peritonitis occurred in 356, 165, and 2,021 patients, respectively. Coagulase-negative staphylococci and Staphylococcus aureus accounted for 48% of relapsing peritonitis (adjusted OR, 1.26 [95% CI, 0.94-1.70] and 1.54 [95% CI, 1.08-2.19], respectively), but were much less likely to be isolated in recurrent peritonitis. Recurrent peritonitis was associated more frequently with fungi (13%; OR, 2.16; 95% CI, 1.12-4.17). The empirical antimicrobial approaches to relapsing and recurrent peritonitis were similar and their subsequent clinical outcomes were comparable. Compared with uncomplicated peritonitis, relapsed and recurrent peritonitis were associated with higher rates of catheter removal (22% vs 30% vs 37%, respectively; P <0.001) and permanent hemodialysis therapy transfer (20% vs 25% vs 32%; P <0.001), but similar rates of hospitalization (73% vs 70% vs 70%) and death (2.8% vs 2.0% vs 1.2%). Limitations: Limited covariate adjustment. Residual confounding and coding bias could not be excluded. Conclusions: Relapsed and recurrent peritonitis are caused by different spectra of micro-organisms, but are not readily clinically distinguishable at presentation. Empirical treatment with broad-spectrum antibiotics and subsequent adjustment according to antimicrobial susceptibilities results in similar clinical outcomes, albeit with appreciably higher rates of catheter removal and hemodialysis therapy transfer than for uncomplicated peritonitis.