We studied prospectively, between 1993 and 1998, the prevalence and incidence of markers against hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis D virus (HDV), in 180 patients with chronic renal failure, dialysed in the Nephrological Clinic, Cluj. HBV and HCV markers were common in the patients who were already on haemodialysis in 1993 (antibodies to hepatitis B core antigen [HBcAb]: 57.9-88%; hepatitis B surface antigen [HBsAg]: 8.7-25%; antibodies to HCV [anti-HCV]: 73.7-100%; simultaneous occurrence of HBsAg and anti-HCV antibodies: 4.4-21%). These patients had the longest mean duration of haemodialysis therapy (6.79 +/- 4.82 years). The lowest prevalence was found in 1996, in the groups of patients included in the haemodialysis programme between 1993 and 1996 (HBcAb: 2.2-3.3%; HBsAg: 0-2.2%; anti-HCV antibodies: 0-2.2%; HBsAg and anti-HCV antibodies: 0-2.2%). The patients included since 1996 had, again, a high prevalence of markers (HBsAg: 21.6%; anti-HCV antibodies: 28.6%), despite the short duration of dialysis therapy (1.65 +/- 1.18 years). The incidence of infection was high before 1993, fell markedly between 1993 and 1996 (zero for the HBsAg and 6. 67% year-1 for the anti-HCV antibodies) and rose sharply between 1996 and 1998 (10.2%, respectively 29% year-1). The prevalence of HBV and HCV infections did not correlate with the age of the patients and depended, but only up to 1993, on the quantity of transfused blood. The link between the duration of the haemodialysis and the prevalence of the HBV and/or HCV infection proved nosocomial transmission. The very high prevalence and incidence of HBV and HCV infections, surpassing not only Western countries, but even those of 'developing' countries that are endemic for these infections, is characteristic of some former communist countries. A radical reform of the medical system in these countries is required.