Study objective - The recent availability of Haemophilus influenzae type b (HIB) conjugate vaccines prompted an examination of the costs and benefits of four and three dose HIB prevention programmes targeting all newborns in Israel. Measurements and main results - A four dose programme would reduce the number of childhood (aged 0.13) HIB cases from 184.2 to 31.3 per year, yielding a benefit ($1.03 million) to cost ($3.55 million) ratio of just 0.29/1 for health services only, based on a vaccine price of $7.74 per dose. When benefits resulting from a reduction in mild handicaps and severe neurological sequelae are included, the benefit ($4.48 million) to cost ratio rises to 1.26/1 and it reaches 1.45/1 when the $0.66 million indirect benefits of reduced work absences and mortality are also included. Break even vaccine costs are $2.24 when health service benefits only are considered and $11.21 when all the benefits are included. Conclusion - In the absence of other projects with higher benefit to cost ratios, Israel should start to provide a nationwide HIB vaccination programme since the monetary benefits to society of such a programme will exceed the costs to society. A barrier to implementation may occur, however, because the costs of the programme exceed the benefits to the health services alone.