The study aimed to estimate the incidence of HCV seroconversion in hemodialysis patients in the Brazilian Unified National Health System (SUS). This was a prospective, non-concurrent study using patients' data identified by deterministic and probabilistic record linkage in the SUS information system. The study included 47,079 patients started on hemodialysis between January 1, 2000, and December 31, 2003, followed until seroconversion or conclusion of the study in 2004. Three percent of hemodialysis patients HCV-seroconverted (1.7 per 100 patient-years). Increased risk of HCV seroconversion was associated with age, glomerulonephritis, geographic region, HIV-positivity, and dialysis service. The observed HCV seroconversion rate was similar to that in developed countries, highlighting evidence of transmission among hemodialysis patients.