In an attempt to evaluate the adequacy of regular dialysis therapy, calculations of Kt/V-urea and protein catabolic rate (pcr) from the data of routine laboratory examinations by means of urea kinetic modeling were performed in 59 regular dialysis patients (28 males and 31 females; mean age, 59 +/- 2 years old; mean dialysis duration, 83 +/- 10 months). The mean values of Kt/V-urea and pcr were 1.10 +/- 0.04 and 0.98 +/- 0.03 g/kgBW.day, respectively. The number of patients who were within the optimal range (0.9-1.4 for Kt/V urea and 0.9-1.5 for pcr) was 37 (62.7%) for Kt/V-urea and 38 (64.4%) for pcr. Furthermore, we inferred that, based on an appropriate dietary protein intake, removal of urea by intermittent dialysis should be adjusted to maintain the patient in equilibrium for a defined pre-dialysis plasma urea concentration. From the data obtained, we concluded that: (1) it is possible to apply urea kinetic modeling on the basis of routine laboratory examinations, (2) it is important to maintain the pre-dialysis plasma urea concentration at more than a certain level, and (3) it is also important to control the post-dialysis plasma urea concentration at a low level.