Fifty-five consecutive patients with end-stage renal disease entering haemodialysis programmes over a two-month period and 48 consecutive recipients of renal allografts during a period of 6 months were investigated for hepatitis B virus (HBV) and hepatitis D virus (delta) infection. HBV markers were present in 25 of the former and 40 of the latter. Of the 65 patients with HBV infection, 12 were not available for delta antibody screening. HBV infection was present for a mean of 2.5 months and 45.3% of those infected had clinical hepatitis; none had fulminant hepatitis. All the patients tested were negative for antidelta antibody. An additional patient on dialysis with delta superinfection and hepatic encephalopathy is also reported.