Widespread vaccination of haemodialysis patients had occurred during the year 1999 as a result of the promulgation of the Ministry of Health & Population. To our knowledge, this might be the first study in Egypt concerning post-vaccination response in haemodialysis patients and possible risk factors influencing this response. Eighty-three haemodialysis patients vaccinated with 10 microg dose of recombinant hepatitis B Merck Sharp vaccine at 0, 1 and 6 months were enrolled in the study. Blood samples were withdrawn one month after the third dose and sera were tested for anti-HBc to exclude those who had previous HBV exposure and for quantitative determination of antibodies to hepatitis B surface antigen (anti-HBs) using commercial enzyme immunoassay kits. Routine analysis for anti-HIV, anti-HCV and HBsAg every 3 months is done for all haemodialysis patients in the governmental sector. Only 65 patients negative for both anti-HBc and HBsAg were considered eligible for evaluating the immunogenicity of the vaccine. Seroconversion rate (anti-HBs>10 mlU/ml) was detected in 64.6% and adequate response (anti-HBs>100 mlU/ml) was achieved in 38% only. Non-responders were 35.4% reflecting the profound immune suppression in haemodialysis patients. Seroconversion rate was 84.2% in patients below 40 years of age and dropped to 33.3% in those 60 years or above. Seroconversion was significantly higher in females than males (76.5% vs. 51.6%). HCV infection was strikingly high among dialyzed patients (78.5%). Seroconversion rate was 58.8% in HCV-infected and 85.7% in non HCV-infected haemodialysis patients. Neither the duration of haemodialysis nor the frequency of blood transfusions had any significant association with seroconversion rate.