The objective was to review the rationale for the Kidney Disease Outcomes Quality Initiative (K/DOQI) recommendations for adequacy of peritoneal dialysis and to evaluate the impact of these recommendations on clinical practice and patient survival. The K/DOQI recommendations were based on large observational studies; the target weekly Kt/V value of 2.0 assumed equivalence of peritoneal and renal clearances. This assumption is no longer considered correct. The impact on clinical practice was evaluated by an examination of temporal trends before and after publication of the guidelines in 1997. In the United States and The Netherlands, there had been a trend toward increased delivered total Kt/V prior to 1997, and there was no acceleration in this trend after 1997. Two randomized clinical trials have implemented these guidelines with increased peritoneal Kt/V (or creatinine clearance) used to achieve the K/DOQI target in the intervention group. This was not associated with improved survival, compared to a lower Kt/V, in either of the randomized clinical trials. Among the explanations for the failure to improve outcome are potential adverse effects of increasing the dialysis dose. These include increased intraperitoneal pressure associated with increased exchange volume, failure to increase clearance of middle molecules, and increased exposure to glucose. Strategies that increase peritoneal clearance without exposure to these potential adverse effects include more-frequent exchanges rather than increased exchange volume, and decreased exposure to glucose and glucose degradation products. Pending such studies, current K/DOQI guidelines should be updated in a timely manner.