[en] In order to evaluate the future burden of hepatitis C, there is a need to quantify the evolution with time of some crucial parameters such as disease frequency and age, modes of infection and infecting genotypes of patients presenting for the first time at consultation. The yearly evolution of these parameters was analyzed retrospectively in a cohort of 1,726 patients living in Belgium, who were diagnosed as hepatitis C virus (HCV) carriers by polymerase chain reaction (PCR) between 1992 and 2002. The epidemiological profile of HCV patients showed significant changes during this period. The number of new patients increased with time. The proportion of patients under 50 increased linearly at a rate of 3% per year. The rate of newly presenting patients infected by transfusion before 1990 decreased, but only by 2.7% per year. The proportion of intravenous (IV) drug users increased by 2.5% per year. Patients presenting "undefined" risk factors increased by 2.1% per year. Nosocomial acquisition of HCV infection exhibited a disturbing relative stability in time whereas dialysis tended to disappear as a cause of infection. There was a significant linear annual decrease of 2.3% in the frequency of genotype 1b, which was counterbalanced by a significant increase of 0.7% for genotype 1a and 1.1% for genotype 4. Genotypes 2 and 3 did not vary significantly with time. Such figures are useful for evaluating the epidemiological changes of C virus infection and for anticipating the future economical cost of hepatitis C treatment in the next few years.