Background. The guidelines published by the NKF-Dialysis Outcomes Quality Initiative (DOQI) in 1997 advocate an earlier start of dialysis in ESRD patients and a higher dialysis dose than usual. We studied the possible influence of the increasing emphasis on adequate dialysis on the management of ESRD patients in The Netherlands in 1993-2000. Methods. The NECOSAD study on the adequacy of dialysis started in 1993. This prospective multi-centre study included ESRD patients older than 18 years who started HD or PD as the first RRT. We analysed the distribution of age, gender, primary renal disease and co-morbidity, the mean residual renal function and the mean dialysis-Kt/V urea at 3 months in 1569 consecutive patients by calendar year of initiation dialysis. Results. Age, gender, primary renal disease and number of co-morbid conditions at the start of dialysis remained stable over time between 1993 and 2000. The mean renal Kt/V urea at 3 months increased from 0.5 in 1993 to 0.8 per week in 2000 (P<0.01). An upward trend remained after adjustment for patient characteristics and dialysis centre. The total Kt/V urea at 3 months increased from 3.3 in 1993 to 3.7 per week in 2000 in HD (P<0.01) and from 2.0 in 1993 to 2.3 per week in 1999 in PD patients (P<0.01). An upward trend in the dialysis-Kt/V urea was found after adjustment for renal Kt/V urea (HD: +0.3 per week, P=0.06; PD, +0.2 per week, P<0.05). Conclusions. These results indicate a tendency towards earlier introduction of RRT and higher doses of dialysis in The Netherlands. Possible effects of this development on mortality, morbidity, quality of life and the balance between costs and benefits need further investigation.