Abstract: The development of peginterferon and ribavirin combination therapy has significantly improved the sustained virologic response (SVR) rates in patients with chronic hepatitis C. However, poor patient adherence to therapy negatively influences drug levels and drug exposure, often preventing the development of an inhibitory drug level. To optimize patient adherence, the clinician must recognize factors predicting low adherence and negotiate a treatment plan that the patient understands and to which he or she commits. If adverse effects become intolerable, continuing patients on a reduced dose rather than withdrawing treatment seems to confer considerable advantage in preserving the chance for attaining an SVR. Results of a head-to-head comparison have demonstrated the possibility that, in cases of dose reduction, levels of peginterferon alfa-2a could remain above the limit of detection, whereas those of peginterferon alfa-2b might not.