The aims of the present study were to profile seroprevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, and possible risk factors among hemodialysis (HD) patients in private hemodialysis units (HDU) in Surabaya, Indonesia. Sera were obtained from 180 HD patients in 4 different private HDUs and tested for hepatitis B surface antigen (HBsAg) and antibody to HCV (anti-HCV). Patients without HBsAg and anti-HCV at first sampling were followed serologically every 3 months for 9 months, while those with HBsAg or anti-HCV positive sera were subjected continually to PCR to detect HBV DNA and HCV RNA. The prevalence of hepatitis infections varied widely between the HDUs, from 0% to 8.1% of patients positive for HBsAg and 0% to 60.6% of those positive for anti-HCV, respectively. These values were markedly higher than those among the general population, but not as high as in governmental HDUs in Indonesia. New incidence of HBV was not detected in any HDU, whereas that of HCV was found in two HDUs, HCV-1b in one HDU and HCV-1a in the other. Inappropriate practices were observed, such as shortage of medical staff and malfunctions in infection-control committees. Prevalence of HBV and HCV infection among HD patients in private HDUs were high and varied among the HDUs. Isolation of both HBV- and HCV-infected patients and staff education should help to reduce the prevalence of hepatitis infections in HDUs.