A dosage regiment for the treatment of a Flaviviridae infection, including a hepatitis C viral infection, that includes administering gemcitabine (or its salt, prodrug or derivative, as described herein) in a dosage range of approximately 50 mg/m<2 >to about 1300 mg/m<2 >per day for between one and seven days (e.g. 1, 2, 3, 4, 5, 6, or 7 days) followed by cessation of therapy. Viral load is optionally monitored over time, and after cessation, viral rebound is monitored. Therapy is not resumed unless a significant viral load is again observed, and then therapy for 1-7 days and more preferred, 1, 2 or 3 days, is repeated. This therapy can be continued indefinitely to monitor and maintain the health of the patient.