The Hepatitis C virus has emerged over the last two decades as the cause of the second greatest viral infection epidemic after the human immunodeficiency virus (HIV). A significant characteristic of the infection with the Hepatitis C virus is the variable course of its natural history. About 80% of the people who acquire this agent develop a chronic infection, with varying degree of liver damage, including cirrhosis and even hepatocelular carcinoma. However, only a minority progresses towards more severe forms. Several factors associated with the host seem to influence the progression of Hepatitis C into cirrhosis. The most important are alcohol abuse, the age in which the infection is acquired, duration of the infection, overweight, male sex and coinfection with Hepatitis A or B or HIV. Evidence of the role of iron levels in the liver, tobacco or the source of infection are less clear. The factors associated with the agent do not seem to play any role in the progression of the disease. Additional studies with adequate control groups are required to confirm the participation of the above mentioned host factors and to identify others which could influence the natural history of the Hepatitis C infection. A reduction in the ingestion of alcohol, overweight and tobacco consumption could contribute to the treatment of HVC chronic infection, as well as vaccination against Hepatitis A and B.