Background. Triage in Preventive Child Health Care (PCH) assessments could further the efficient use of human resources and budgets and therefore make extra care possible for children with specific needs. We assessed the costs of routine PCH assessments with and without triage for children aged 5/6 years and 10/11 years. In a triage approach, PCH assistants conduct pre-assessments to identify children requiring follow-up assessments by a physician or nurse. In the usual approach, all children are assessed by a physician and an assistant (children aged 5/6 years) or a nurse (children aged 10/11 years). Methods. All the direct costs of conducting routine PCH assessments with the triage and usual approach were assessed using a bottom-up micro-costing approach. In four PCH services in the Netherlands, two using triage and two the usual approach, professionals completed questionnaires about time spent on assessments, including time related to non-attendance at assessments, the referral of children and administration. Results. The projected costs for PCH professionals working on PCH assessments amounted to €5.2 million per cohort of 100,000 children aged 5/6 years in the triage approach, and €7.6 million in the usual approach. The projected costs in both approaches for children aged 10/11 years were about €4 million per 100,000 children. Conclusion. The triage approach to PCH resulted in a projected cost reduction of about one-third, compared with usual practice, for routine assessments by physicians of children aged 5/6 years. There are minimal cost savings in the group of children aged 10/11 years when nurses are involved and so other considerations such as workforce shortages would be required to justify a change to a triage approach. Further research is needed to investigate the differences in costs of care after the completion of the routine assessments.