The effect of hepatitis C virus (HCV) and its treatment on survival is not well defined. We undertook this study to determine the effect of HCV and its treatment on survival in a national cohort of HCV-infected veterans and uninfected controls. We used a national sample of HCV-infected persons and HCV-uninfected controls from the Electronically Retrieved Cohort of HCV Infected Veterans (ERCHIVES) to compare survival between the two groups. We also compared the effect of treatment and treatment duration on survival in the HCV-infected group. We used matched Cox proportional hazards model to determine the predictors of mortality. Kaplan-Meier survival plots were generated to determine and compare survival among HCV-infected and HCV-uninfected persons, and among treated and untreated HCV-infected persons. We identified 34,480 matched pairs of HCV-infected subjects and controls. HCV infection was independently associated with a higher risk of mortality (hazards ratio, 1.37; 95% confidence interval, 1.31-1.47). Subjects treated for 48 weeks or longer had the lowest mortality among HCV-infected subjects (hazards ratio, 0.41; 95% confidence interval, 0.27-0.64), whereas those who received less than 48 week of treatment had intermediate mortality ( I t is estimated that more than 170 million persons are infected with the hepatitis C virus (HCV) worldwide. 1 HCV infection is a leading cause of liver cirrhosis, end-stage liver disease, hepatocellular carcinoma, and liver transplantation. 2,3 Treatment for HCV is associated with a reduced risk of liver disease progression and a lower incidence of hepatocellular carcinoma, even when the treatment does not achieve viral eradication. [4][5][6] The impact of HCV infection on survival in the general population is controversial. Some studies have shown a significant increase in mortality in HCV-infected persons, 7,8 whereas others have shown relatively low mortality rate and liver disease progression in otherwise healthy persons. 9,10 In subsets of patients who have undergone liver transplantation, who have human immunodeficiency virus coinfection, or those on hemodialysis, HCV is associated with significantly shortened survival. [11][12][13][14][15][16] Treatment for chronic HCV has been found to be cost-effective 17 and is associated with sustained viral clearance in approximately 54% to 63% of patients overall. [18][19][20][21] However, the effect of HCV infection itself and its treatment on longterm survival is not well known. We used a large national electronically retrieved cohort of HCV infected veterans (ERCHIVES) to compare survival between HCV-infected and HCV-uninfected subjects and to determine the effect of HCV treatment on survival within the HCVinfected subjects. Our study does not attempt to define or determine the appropriateness of treatment initiation,