The objective of this study is to determine the effectiveness of PEG-Intron 1.5 ug/kg/wk plus REBETOL (ribavirin) 800-1400 mg/day in adults with chronic hepatitis C with moderate to severe liver fibrosis or cirrhosis who failed to respond to previous treatment with an alpha interferon in combination with ribavirin. Patients who do not respond to PEG-Intron plus REBETOL (ribavirin) will be enrolled in a long-term maintenance study to evaluate the effectiveness of PEG-Intron monotherapy versus no treatment for the prevention of disease progression (Protocols P02569 and P02570).