OBJECTIVES: To estimate: (i) the current rotavirus burden in New Zealand children less than 5 years of age; and (ii) the annual health benefits, budget impact and cost- effectiveness of including Rotateq, a pentavalent live-attenuated oral rotavirus vaccine, in the annual Childhood Immunisation Schedule. METHODS: A spreadsheet model was based on local epidemiology and costs plus the findings of a large phase III clinical trial showing that RotaTeq had 94.5% efficacy against rotavirus hospital presentations and 86.0% against non-urgent medical visits. In the base case, vaccine uptake was 85% and the annual discount rate was 5%. RESULTS: We predict annually 1356 admissions, 2781 ED presentations and 9495 primary-care consultations at an annual societal cost of $7.8M ($27.68/child; two-thirds Government, one-third caregivers). Vaccinating successive birth cohorts becomes increasingly effective and cost-effective as more children become immune. After five years (assuming 85% annual uptake of 3 doses), 7936 cases seeking medical attention (1105 admissions, 2215 ED presentations, 6941 primary-care consultations) would be averted. At an acquisition cost of $50/dose, the incremental cost to Government is $6.41M in year-1 and $3.35M in year-5. Societal cost in year-5 would be $1301 to avert one hospitalisation and $139 to avert one healthcare presentation. The annual cost to Government is $3.38M to avert 7936 cases of paediatric rotavirus gastroenteritis that would otherwise require medical attention. The incremental cost and cost/admission averted are moderately sensitive to rotavirus incidence rates, declining protection over 5 years (if any), and vaccine unit price, but robust to uncertainty in other parameters. The budget impact of vaccination will lessen slightly and the cost-effectiveness will improve slightly beyond year-5, provided protective efficacy is maintained in school-aged children. CONCLUSION: Addition of a pentavalent rotavirus vaccine to the New Zealand Childhood Immunisation Schedule would confer important clinical gains at a modest annual cost.