Studies on chronic viral hepatitis and mortality have often been made on selected populations or in high-endemic countries. The aim of this study was to investigate the causes of death and the mortality rates in the nationwide cohorts of people chronically infected with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) in Sweden, a low-endemic country. All notifications on chronic HBV infection and HCV infection 1990-2003 were linked to the Cause of Death Register. A total of 9517 people with chronic HBV infection, 34 235 people with HCV infection and 1601 with chronic HBV-HCV co-infection were included, and the mean observation times were 6.4, 6.3 and 7.9 years, respectively. The mortality in the cohorts was compared with age- and gender-specific mortality in the general population and standardized mortality ratios (SMR) were calculated. All-cause mortality was significantly increased, SMR 2.3 (HBV), 5.8 (HCV) and 8.5 (HBV-HCV), with a great excess liver-related mortality in all cohorts, SMR 21.7, 35.5 and 46.2, respectively. In HCV and HBV-HCV infected there was an increased mortality due to drug-related psychiatric diagnoses (SMR: 20.7 and 27.6) and external causes (SMR: 12.4 and 11.4), predominantly at younger age. To conclude, this study demonstrated an increased all-cause mortality, with a great excess mortality from liver disease, in all cohorts. In people with HCV infection the highest excess mortality in younger ages was from drug-related and external reasons.