Résumé : Liver dysfunction was observed in 33% of patients treated by hemodialysis and kidney transplantation. Fifty-eight percent of these cases of hepatitis occurred in patients with past or present HBs antigenemia, and 77% of HBsAg-positive patients showed evidence of LD. However, during the course of a program conducted from 1969 to 1976 and involving 267 patients, the decrease in the prevalence of HBs antigenemia observed during the last two years did not lead to any reduction in LD incidence. In a small number of patients, potentially hepatotoxic drugs could be incriminated, but in our experience azathioprine never appeared to be involved. In a few patients, LD was due to granulomatous disease of the liver, such as tuberculosis and schistosomiasis. Twenty-one (7%) of the 267 patients at risk developed chronic hepatitis, which contributed to death in nine patients. In 12 cases (three deaths), this form of hepatitis occurred in HBsAg-positive patients, and in nine cases (six deaths), in HBsAg-negative patients. In three of these latter individuals, cytomegalovirus could be incriminated. Routine monthly screening for CMV in kidney recipients confirmed the high incidence of this viral infection in such patients. Studies on murine CMV infection have demonstrated that this infection can be enhanced by histoincompatible graft or by cyclophosphamide in a model that is very close to the kidney recipient. As in mice, CMV infection in kidney recipients apparently results from reactivation of a latent infection. It seems to play a major role in the LD observed and could apparently lead to chronic hepatitis and even to cirrhosis of the liver. Finally, the occurrence of LD in HBsAg-, anti-HBs- and antiCMV-negative patients would suggest the responsibility of other viruses for the pathogenesis of liver disease in patients treated by hemodialysis and kidney transplantation. Besides Epstein-Barr virus, other viruses, such as hepatitis C virus, should be thoroughly scrutinized.