Introduction: There is little experience with the nationwide implementation of an evidence-based pediatric guideline on first-choice fluid for resuscitation in hypovolemia. Methods: We investigated fluid prescribing behavior at (1) guideline development, (2) after guideline development, and (3) after active implementation and identified potential barriers and facilitators for guideline implementation. In order to minimize costs and to optimize implementation effect, we continuously developed and adjusted implementation strategies according to identified barriers. Implementation success was evaluated using questionnaires, pharmaceutical data, and data from medical records. Discussion: The most remarkable change occurred after guideline development and dissemination: Normal saline use by neonatologists increased from 22-89% to 100% and by pediatric intensivists from 43-71% to 88-100%, and synthetic colloid use by pediatric intensivists declined from 29-43% to 0-13% with a reduction in albumin use by neonatologists from 11-44% to 0%. After active guideline implementation, most of specialist's management behavior was according to the guideline. Conclusion: Stakeholders involved in the developmental process are of great importance in disseminating recommendations before active implementation. Therefore, to successfully implement guidelines and reduce costs of active implementation, any guideline development should consider implementation right from the beginning. Implementation strategies should target identified barriers and will therefore always be guideline specific. © 2009 The Author(s).