Three hundred eighty-eight sequential reverse dextrose clearances (RDC) have been performed in 61 unselected patients (12 of whom were diabetics), whose mean age was 54 years (30-79). They were treated for a mean time of 23 +/- 12 months (0-60); the total observation time was 1,440 months. One hundred forty-two episodes of peritonitis were registered, producing a peritonitis incidence of 1 episode per 10.2 patient months. The RDC values are significantly inversely related to dwell-time and show a tendency to increase over time; they never, however, reach statistical significance. Age of patients, episodes of peritonitis and primary renal disease (diabetes) had no influence. It is important to underline the significant inverse relationship between ultrafiltration and residual diuresis. Unknown mechanisms regulate this relationship.