We studied morbidity in 648 patients treated in our center in a ten-year period as indicated by duration of hospitalization: 232 patients were on CAPD, 188 on hemodialysis (HD) and 228 had cadaveric kidney transplants (Tx). Duration of hospitalization was divided into four groups according to its causes. The age of the patients on CAPD was 61 +/- 14 years, 53 +/- 17 on HD and 36 +/- 10 in the Tx group. The total follow-up was 629 patient-year (p-y) on CAPD, 458 p-y on HD and 928 p-y on Tx. The first admission was longer on CAPD (30 +/- 18 days) and on Tx (36 +/- 18 days) than on HD (18 +/- 12). After the first admission, the total days of hospitalization (days/patient-year, d/p-y) were more for CAPD than HD and Tx. Analysis of these data showed that the difference was due to peritonitis and to the different percentage of elderly patients in the CAPD group. With a reduction in the incidence of infectious complications (peritonitis, tunnel or exit-site), hospitalization in CAPD could be reduced to a length of time similar to that currently needed by HD and Tx patients. This can result in important cost-saving.