The epidemiology data of renal replacement therapy are collected by national renal registries and extended to international registries as the European Renal Association Renal Registry. The extent and accuracy of data vary widely among countries. The aim of this study was to compare combined data from the national renal registries of Balkan countries contributing the ERA-EDTA Registry or from other sources, with combined data from renal registries of the Western and Northern European Countries and regions contributing the ERA-EDTA Registry. Data regarding incident and prevalent patients in 2003, mean age of incident and prevalent patients, incidence and prevalence by cause of renal failure and prevalence by established therapy were compared between the countries of the Balkan region and the countries of Western and Northern Europe contributing to the ERA-EDTA Registry. Data were obtained by the Annual Report 2003 of the ERA-EDTA Registry, and for Romania by the study of G. Mirescu published in NDT 2004. Some data were obtained by the questionarries sent to people responsible for the national registries. The results showed the following: the incident number of patients per million population (pmp) at day 1 of RRT, as well as at day 91, adjusted for age and gender, did not statistically differ between the Balkans and Western Europe: 119.2 +/-25.1 vs. 123.3 +/- 25.9 and 110.9 +/- 34.7 vs. 106.5 +/- 18.3, respectively. The mean age of incident patients at day 91 of RRT significantly differed between the Balkans and Western Europe, 57.7 +/- 4.49 vs. 63.3 +/- 2.2, p < 0.005. The percentage of incident patients by cause of renal failure at day 91 of RRT did not significantly differ between the Balkans and Europe. The mean incidence of the percentage of DM as a cause of renal failure between the Balkans and Western Europe did not differ, 23.05+/- 4.5 vs. 20.3 +/- 7.2. When adjusted for age and gender, the significant difference in prevalent number of ESRD patients between the Balkans and Western Europe disappeared. The mean age of prevalent patients between the Balkans and Europe did not significantly differ, 54.3 +/- 4.2 vs. 58.2 +/- 2.8. The percentage of primary renal disease in prevalent patients did not significantly differ, except for policystic kidney disease which is significantly more frequent in Western Europe compared to the Balkans, 9.2 +/- 1.9 vs. 6.8 +/- 1.8, p < 0.01. Diabetes mellitus and hypertensive nephropathy are much more frequent in incident patients compared to prevalent ones. Transplantation is significantly more frequent in Western Europe, predominantly cadaveric, whereas dialysis is more frequent in the Balkans. It can be concluded that no difference exists between the incidence and prevalence of diabetes mellitus as a primary renal disease in ESRD patients between the Balkan and European countries, indicating that the epidemic of diabetes is already present in the Balkans and imposing, perhaps, efforts to be undertaken for planning prevention strategies; kidney transplantation is significantly less represented as RRT in Balkan countries compared to Western and Northern Europe, and efforts should be made for its increase, particularly the cadaveric one, and moreover, because the population on RRT is significantly younger in the Balkans.