The objective of the present study was to assess the economical impact of invasive Haemophilus influenzae type b infections in Slovenia, where the annual incidence of these infections is 16.4/100000 in children less than 5 years of age, and to compare it with the costs of a vaccination programme. The lifetime costs and benefits were estimated for the annual birth cohort of 18200 children. In the base-case model, the calculated benefit-to-cost ratios were 0.15, 0.98 and 1.38 taking into account 95% of savings in acute care costs, medical costs, and medical and non-medical costs, respectively. From the point of view of the Institute of Health Insurance of Slovenia, who pays all healthcare and vaccination costs, the vaccination programme per annual birth cohort of 18200 children would require an extra 7023 EUR or 0.40 EUR per cohort-child. The savings to society would represent 118410 EUR, indicating the rationale for inclusion of H. influenzae type b vaccination in the routine childhood immunisation programme in Slovenia.