Acute hepatitis C virus infection is associated with high rates of spontaneous clearance and variable rates of treatment-induced clearance. The benefit of early treatment versus awaiting spontaneous clearance is unknown, as is the optimal timing of treatment.We performed a MEDLINE and EMBASE search for the time period 1950 to October 2008. All English language abstracts using the search terms acute hepatitis C, hepatitis C and acute and hepatitis C and acute disease or acute infection were reviewed. Bibliographies were reviewed.Twenty-two studies including 1075 patients met the inclusion criteria. The sustained virologic response (SVR) rate for treated patients was 78%, significantly higher than 55.1% in untreated patients (OR = 3.08, 95% CI: 1.8-4.8 P value <0.0001). Mean time from diagnosis to spontaneous clearance was 9.7 weeks (SD 6.5). SVR rates varied inversely with time from acute HCV diagnosis. SVR rates for treatment within 12 weeks was 82.5% (95% CI: 75.6-89.3), significantly better than the clearance rates in untreated patients (P < 0.001). Response rates fell to 66.9% for treatment between 12 and 24 weeks, and decreased further to 62.5% for treatment beyond 24 weeks. Rates of viral clearance in treated patients with acute hepatitis C virus infection were significantly higher than that in untreated patients. Treatment rates were highest when treatment was initiated within 12 weeks of diagnosis. Based on these findings, we would advocate a 12 week period of observation for spontaneous clearance before treatment initiation. If no clearance has occurred by 12 weeks, treatment should be initiated.