BACKGROUND Two rotavirus (RV) vaccines (Rotarix and RotaTeq) are available on the private market in Taiwan, but are not recommended for routine use. We examined RV vaccine effectiveness (VE) against severe RV acute gastroenteritis (AGE) among Taiwanese infants to inform policymakers on the potential benefits of national RV vaccine introduction. METHODS From May 2009 to April 2011, a case-control assessment of VE against severe RV AGE was conducted at 3 hospital-based surveillance sites in Taiwan. Case-patients included children aged 8-35 months, hospitalized with laboratory-confirmed RV AGE. Controls included children age-matched within 1 month of age of the case-patient, hospitalized with RV-negative AGE or seen for non-AGE illnesses at the same hospitals. Vaccination history was confirmed through vaccination card or hospital record review. VE was calculated as (1--odds ratio of vaccination) × 100%. RESULTS We enrolled 184 case-patients with RV AGE, 904 RV-negative AGE and 909 non-AGE controls. Two-dose Rotarix series VE against RV gastroenteritis hospitalization was 90.4% [95% confidence interval (CI): 70.3%, 98.1%) and 92.5% (95% CI: 77.1%, 98.5%) with RV-negative AGE and non-AGE controls, respectively. Three-dose RotaTeq series VE was 96.8% (95% CI: 82.3%, 100%) and 97.1% (95% CI: 84%, 100%) with RV-negative AGE and non-AGE controls, respectively. CONCLUSIONS Both vaccines provided excellent protection against severe RV AGE hospitalization. Addition of RV vaccination into Taiwan's National Immunization Program could substantially decrease AGE hospitalizations among children <3 years. Our findings should help inform policymakers in Taiwan and other similar Asian countries when deciding whether to include RV vaccination into their national immunization programs.