In 1989, the main agent causing non A non B hepatitis was identified as a RNA virus of the flavivirus family, with several serotypes, and was denominated virus C. At the present moment, the knowledge about the infection features and diseases that it causes has expanded thanks to the availability of reliable laboratory techniques to detect the antibody and the virus. The prevalence of infection and the frequency of serotypes varies in different regions of the world. Chile is a country with a low prevalence. The detection of infected blood in blood banks has reduced the spreading of the disease. Other means of infection such as the use of intravenous drugs, hemodialysis and transplantation have acquired greater importance. Sexual, maternal and familial transmission is exceptional. Infected people develop an acute hepatitis, generally asymptomatic. Eighty percent remain with a chronic hepatic disease, that can be mild or progressive, evolving to cirrhosis or hepatic carcinoma. Chronic hepatitis, closely resembling an autoimmune disease, can be caused by the virus. Alcohol intake increases viral activity causing severe hepatic diseases, refractory to treatments. Several non hepatic diseases are associated to hepatitis C virus infection such as essential mixed cryoglobulinemia, mesangiocapillary glomerulonephritis, porphyria cutanea tarda, dysglobulinemias and probably type 2 diabetes mellitus. The only available treatment is interferon, that is successful in a minority of patients, frequently causing a transient improvement. The use of Ribaravine associated to interferon improve the effectiveness of therapy. Liver transplantation is the only therapy for severe hepatic disease. The use of new antiviral drugs should improve the prognosis of the disease.