More than 180.000 children and adults in the Netherlands are affected by an inborn bleeding disorder. They experience frequent bleeding episodes which cause extreme discomfort, invalidity due to joint and muscle bleeds, and sometimes death. Personalisation of treatment is urgently needed. It will safeguard quality of care while restraining rising costs in these debilitating and expensive diseases. Current treatment strategies are suboptimal and lead to either under treatment with risk of continued bleeding or overtreatment with excessive costs. Novel therapeutic approaches are upcoming and expected to be even more expensive. However, effectiveness, (long term) side effects and therefore, positioning and optimal use of these new treatments is not clear. Better insight into the pathophysiology of these diseases is required in order to develop more precise diagnostic techniques. Moreover, safe therapeutic approaches with minimal complications and their cost-effective patient orchestrated implementation are warranted. In this study proposal, we present a step-wise approach by an interdisciplinary team of experts in collaboration with stakeholders, to achieve 1) precision diagnosis; 2) to develop and implement safe and cost-effective treatment strategies; while 3) integrating yields of translational research. Highlights of the study are the development and systematic measurement of both patient-relevant outcome measures as well as costs of treatment, according to value-based health care methodology. In addition, e-health modules will aid implementation of treatment innovations and measurement of outcomes. Moreover, advanced laboratory techniques will be applied to develop novel diagnostic tests and to perform proteomic profiling to explain the interindividual variation of clinical manifestations in these bleeding disorders. Ultimately, the SYMPHONY consortium aims to identify best treatment choice for each individual with a bleeding disorder. Jointly, composing life-changing innovations with significant clinical and societal impact.