Young people face many barriers in accessing health services that are responsive to their needs. The World Health Organization has led a call to develop services that address these barriers, i.e. youth-friendly health services. Addressing the needs of young people is one of the priorities of Foundation fami, an organisation working in collaboration with the Swiss Federal Department of Development and Cooperation and Geneva University Hospitals to develop quality family medicine services in Bosnia and Herzegovina. This paper describes the design of a trial to assess the effectiveness of a multifaceted intervention involving family medicine teams (primary care doctors and nurses) to improve the youth-friendliness of family medicine services in Bosnia and Herzegovina.