The natural history is the expected course in a particular disease.
In the majority of diseases, it is well known what will occur when someone has a disease and receives no treatment. Hepatitis C does not always follow a particular set of rules. It is estimated that if left untreated, hepatitis C has the potential to progress to cirrhosis in 15% of the cases over a 20-25 year span. Individuals who consume alcohol or have other diseases of the liver may develop cirrhosis in a shorter period of time.
There are many factors that affect the natural history of hepatitis C, all of which need to be discussed with the patient.