OBJECTIVES: To compare two combined vaccination strategies against hepatitis A and hepatitis B (at age 1-15 years or at age 11-15 years) with non-vaccination in children and youth, to analyse net-costs per strategy, cost-effectiveness and epidemiologic development in projection for the next 30 years in Germany. METHODS: A period of 3 times 10 years is given, modeling present data on birth rate development, incidence and course of disease and treatment costs per case, calculating incidence, cases of infection resp. disease and treatment costs, calculated from the TPP’s perspective. Costs per case and courses were obtained retrospectively from standardized interviews with pediatricians and from the literature. Cost-effectiveness is assessed as costs per avoided hepatitis A or hepatitis B infection for each strategy. RESULTS: Significant drop in HAV and HAB incidence in vaccinated age groups: Through vaccination of all 1-15 year old children, a reduction of 57 600 new HAV infections and of 45 800 new HBV infections in 30 years can be demonstrated. In the vaccination group 11-15 years, 19 800 new infections with HAV and 21 900 new infections with HBV can be avoided. Vaccination costs over 30 years amount to 1.5 billion DM in the vaccination strategy 11-15 years and 3.7 billion DM in the vaccination strategy 1-15 years. Significant decrease in new infections saves treatment costs of 1.6 billion DM for the vaccination at age 11-15 years and 2.8 billion DM for the vaccination at age 1-15 years. The cost-effectiveness of vaccination ranges from costs of 90 100 DM up to savings of - 20 200 DM per avoided infection, depending on cycle and vaccination strategy. Considering unreported cases of hepatitis A and B as 5 fold of known incidence, the range of savings per avoided infection is between - 3 300 DM and - 38 700 DM. CONCLUSION: The initially more expensive combined vaccine represents a cost-effective alternative to the sole hepatitis B vaccination and also shows a more beneficial effect from an epidemiological point of view. In Germany, the strategy of vaccination between 11-15 years seems to be the most cost-effective - on the other hand the vaccination of all between 1-15 years is superior considering the epidemiological effects.