Nursing support might help patients with chronic hepatitis C (CHC) remain in good mental and physical condition during interferon (IFN) therapy. However, the effects of nursing support have not been studied adequately in this context. This case-control study evaluated the effects of nursing support during IFN therapy. Twenty-four CHC patients who received pegylated IFN and ribavirin were enrolled. Nurses advised patients on the maintenance of their mental and physical condition at weekly visits, based on the results of written questionnaires. An additional 24 patients who received IFN therapy without nursing support and who were matched for age, sex, platelet count, viral serogroup and IFN regimen were selected with propensity score matching as controls. The patients with nursing support during IFN therapy achieved higher sustained virological responses (79%) than those without nursing support (58%). Adherence to the IFN and ribavirin regimens at 24 weeks of therapy were slightly higher in the patients with nursing support than those without it, but these differences were not statistically significant. Adherence to ribavirin after 24 weeks of therapy was significantly higher in those with nursing support than those without it (93% and 66%, p = 0.045). These results suggested that nursing support services could contribute to the virological responses of CHC patients by promoting drug-regimen adherence.