Chronic hepatitis C virus (HCV) infection increases the risk for several types of cancer, including hepatocellular carcinoma (HCC) and B-cell non-Hodgkin lymphoma, as primary and second primary malignancies. HCV-infected patients with cancer, particularly those undergoing anticancer therapy, are at risk for development of enhanced HCV replication, which can lead to hepatitis flare and progression of liver fibrosis or cirrhosis. Risk factors for HCV infection include injection drug use, blood transfusion, or solid organ transplantation before 1992, receipt of clotting factor concentrates before 1987, long-term hemodialysis, chronic liver disease, HIV positivity, and occupational exposure. Widely available direct-acting antivirals are highly effective against HCV and well tolerated. Identification of HCV-infected individuals is the essential first step in treatment and eradication of the infection. One-time screening is recommended for persons born from 1945 to 1965; screening is also recommended for persons with risk factors. Recently, a public health recommendation has been drafted to screen all adults age 18 to 79 years. Two oncology organizations recommend screening all patients with hematologic malignancies and hematopoietic cell transplant recipients, and a recently published multicenter prospective study supports universal HCV screening for all patients with cancer. HCV screening entails testing for anti-HCV antibodies in serum and, when results are positive, HCV RNA quantitation to confirm infection. Direct-acting antiviral therapy eradicates HCV in almost all cases. Virologic cure of HCV prevents chronic hepatitis and progression to liver fibrosis or cirrhosis. HCV eradication also decreases the risk of developing HCV-associated primary and second primary malignancies, and it may allow HCV-infected patients access to important cancer clinical trials. Patients with HCV-related cirrhosis require lifelong surveillance for HCC, even after viral eradication.