This study is divided into 2 segments, and proposes to qualify fine needle aspiration (FNA) as a platform to evaluate the hepatic pharmacokinetics of low and high oral doses of Grazoprevir (MK-5172) in non-cirrhotic participants chronically infected with hepatitis C virus (HCV). The first segment, is a procedural pilot conducted prior to the main study, that is aimed at ensuring optimal execution of the FNA procedure. During the procedural pilot, core needle biopsy (CNB) will be performed on participants as part of their standard of care, but no study drugs will be administered, nor will any procedures other than FNA be conducted. The second segment, the main study, is designed to evaluate the feasibility of measuring Grazoprevir by FNA. During the main study, drugs will be administered, and other additional procedures will be conducted.

Inclusion Criteria:

• Has chronic compensated HCV infection.
• No contraindications to CNB or FNA procedures.
• Pilot study only: All comers with chronic HCV already scheduled to undergo CNB for fibrosis staging.
• Pilot study only: Requires a diagnostic liver biopsy to monitor progression of liver disease.
• Pilot study only: Does not have cirrhosis.
• Main study only: Males or non-pregnant and postmenopausal females willing to use medically acceptable contraception during, and for 6 months or longer after study.
• Main study only: Body mass index of 18.5 - 32.0 kg/m^2.
• Main study only: Can avoid aspirin, anticoagulants, and non steroidal inflammatory agents.
• Main study only: Has undergone prior treatment or is treatment naive for chronic HCV infection.

Exclusion Criteria for Main study only:

• History of any of the following: stroke, chronic seizures, major neurological disorders, gastric bypass surgery or bowel resection.
• No viral response to prior interferon based therapy.
• Prior treatment for HCV with an NS3/4A protease inhibitor.
• History of either clinically significant, uncontrolled endocrine, gastrointestinal, cardiovascular, hematological, immunological, renal, respiratory, or genitourinary abnormalities/diseases.
• History of neoplastic or myeloproliferative disease.
• Has any of the following : cirrhosis, decompensated liver disease, or other advanced liver disease, hepatocellular carcinoma, infection with human immunodeficiency virus (HIV), or hepatitis B.
• Evidence of high grade bridging fibrosis from prior liver biopsy or chronic hepatitis not caused by HCV.
• History of illicit drug use or alcohol abuse.
• Had surgery, donated at least one unit of blood, or participated in any other investigational study within 4 weeks prior to screening visit.
• History of multiple and/or severe allergies.