Eighteen patients on chronic dialysis (15 haemodialysis, three peritoneal) were evaluated to determine whether certain clinical features and/or in vitro indicators of immune function correlated with the response to hepatitis B vaccine. Only 44% of patients developed antibody to hepatitis B surface antigen (anti-HBS) following vaccination and neither duration of dialysis, history of renal transplant, peripheral T cell numbers, T4/T8 ratios, nor mitogen induced lymphocyte proliferation correlated with response to vaccination. Advanced age, history of multiple blood transfusions and depressed levels of IgM may be associated with a poor antibody response to the vaccine. Future studies need to consider these variables when evaluating immunogenicity of new hepatitis B vaccine preparations.