The primary objective of this study is to determine the safe and effective dose range of boceprevir (SCH 503034) in combination with PEG-Intron in adult subjects who have chronic hepatitis C without cirrhosis, and who have failed an adequate course of combination therapy with peginterferon-alfa plus ribavirin. A secondary objective is to explore whether ribavirin provides an additional benefit when combined with PEG-Intron plus boceprevir.