The demography of renal replacement therapy up until the close of 1984 in Europe is presented, based on return of individual patient questionnaires to the EDTA Registry. These were completed by 84.7% of known centres in 33 countries. Of 187,267 individually registered patients, 102,276 were known to be alive on defined forms of renal replacement therapy on 31 December 1984. The stock of patients alive on treatment by dialysis and transplantation in Europe continued to grow and exceeded 200 per million population in 14 European countries at the end of 1984. During the same year, 21,198 new patients were accepted for treatment in Europe, and crude acceptance rates for new patients exceeded 60 per million population in four countries. Acceptance rates for elderly patients continued to increase and age specific acceptance rates for males aged 65 and over exceeded 100 per million population in 12 countries. A total of 6802 renal transplants were reported during 1984. Regrafting accounted for a higher proportion of transplants in Nordic countries and in the United Kingdom, compared with other nations. During 1984 the total number of transplants reported to the Registry passed 50,000. The distribution of primary renal disease amongst adult patients commencing treatment in 1984 is presented. Amongst elderly patients commencing treatment, a strikingly high proportion have chronic renal failure of uncertain aetiology. Finally, causes of death have been analysed amongst adult patients dying during 1984, showing myocardial ischaemia and infarction to be the leading cause of mortality.