OBJECTIVES: Childhood immunizations are recognized as one of the most cost-effective health interventions.  Yet little is know about the actual delivery costs, or variation in costs by service providers and geographic regions.  This study undertook an economic analysis of public health delivery of childhood immunizations in Nova Scotia. METHODS: The analysis was performed from the perspective of the government health care provider for a one-year period from April 2005 to March 2006.  An incremental approach was used to assess the cost of delivering childhood immunizations in addition to existing services.  Primary cost data collected included capital and recurrent costs.  Total provider economic costs were estimated using a combination of ingredients-based costing and step-down cost allocation methodologies.  Sensitivity analysis was used to examine the influence of data uncertainty on cost results.  Multivariate econometric analysis was used to estimate cost functions. RESULTS: Data was collected from four District Health Authorities in Nova Scotia, representing the delivery of 2951 immunizations.   Average cost per immunization ranged from $51to $105 when delivered in main public health offices and $45 to $150 when delivered in off-site clinics.  The main cost driver was personnel costs.  Econometric analysis showed a link between average cost and volume of service delivery. CONCLUSIONS: The cost of public health delivery of childhood vaccines varies according to the volume of services delivered and the delivery setting. The approach developed can be applied to the introduction of new vaccines such as human papilloma virus.  Public health delivery of vaccines can be efficient if programmed on the appropriate scale.