Reactivation of hepatitis B virus (HBV) infection in asymptomatic hepatitis B surface antigen carriers undergoing chemotherapy or immunosuppressive therapy is a well-documented complication. However, data on the consequence of chemotherapy on the course of hepatitis C virus (HCV) infection in HCV(+) patients have been controversial. Here, we review the current knowledge about the complications related to HCV in lymphoma patients receiving chemotherapy/immunosuppressive therapy. Although less frequent than HBV, these complications occur in a subset of patients with mortality rates up to 45%. Therefore, baseline screening for HBV and HCV before initiation of chemotherapy is crucial. High-risk patients having chronic active hepatitis, high baseline HCV viral load, HBV co-infection and receiving cytotoxic drugs, corticosteroids and rituximab (particularly if combined) should be closely monitored for serum transaminase, bilirubin and HCV RNA levels.