Urea kinetic modeling (UKM) is often regarded as the best method for assessing the dialysis adequacy and consequently for the prescription of treatment time. However, other parameters are involved in the monitoring of end stage renal disease (ESRD) patients. Kt/V-urea and protein catabolic rate (pcr) were evaluated in 53 ESRD patients (25 males and 28 females; mean age, 60 +/- 2 years old; mean duration, 80 +/- 11 months), twice at an interval of 4 months, and pre-dialysis concentration of (pre-DC) plasma potassium, bicarbonate, calcium and phosphate were measured. The pre-dialysis systolic blood pressure and hematocrit were also recorded. The numbers of patients who were within the optimal range of Kt/V-urea and pcr recommended by Gotch and Sargent were 36 (67.9%) and 39 (73.6%), respectively, at the first control period, and 39 (73.6%) and 44 (83.0%) at the second control period. However, only about 50% of the patients were within the optimal range of pre-DC plasma calcium, phosphate and bicarbonate. Furthermore, very few patients fulfilled the conditions for all the parameters. It is concluded that (1) UKM is required to describe the domain of dialysis prescription, and (2) other parameters which are not dependent so much on dialysis should be taken into account for assessing the adequacy of dialysis.