['Many preventative strategies have been proposed to control hepatitis C virus (HCV) infection in the hemodialysis unit. The effectiveness of isolation as a preventive policy remains unclear. The aim of this study was to evaluate the effect of an isolation policy on the incidence of hepatitis C in our hemodialysis unit.', 'A total of 325 hemodialysis patients with a mean age of 62 +/- 14 years and a mean duration of dialysis of 4.8 +/- 4.4 years, who were treated from January 1993 to December 2000 were included in this retrospective study. Data were collected from medical records. HCV antibody was monitored at 6-month intervals. During the period before September 1997 all patients were dialyzed in a single room. Isolation started after September 1997, when an additional room became available. Patients positive for either hepatitis B or C were clustered in 1 area (Area 1). Anti-HCV-negative and hepatitis B surface antigen (HBsAg)-negative patients were assigned either to a segregated zone (Area 2) adjacent to Area 1 in the same room or to a separate independent room (Area 3). Dialyzers were not reused and hygienic precautions remained the same throughout the study period.', 'Forty months after the implementation of the isolation policy, there was significant reduction in the total prevalence (49.7 vs 31.7%, p < 0.01) and incidence (9.1 vs 2.9 % patient-years, p < 0.01) of HCV infection. Seroconversion of anti-HCV was detected in 9 patients, 7 in Area 1, 2 in Area 2, with no new cases in Area 3. The incidence of seroconversion of anti-HCV was significantly different in the 3 areas. Regression analysis indicated that isolation was the most prominent independent factor in reducing seroconversion of anti-HCV.'] Does isolation effectively prevent the transmission of hepatitis C virus in the hemodialysis unit?