Fetal tachyarrhythmias are a life-threatening condition complicating a small proportion of normal pregnancies. Despite major advances in the (intrauterine) pharmacologic treatment of these arrhythmias over the last years major uncertainties remain. Among these are controversies in the choice of agents in relation to arrhythmia type, and timing and duration of treatment. Currently, no evidence-based approach to the management of fetal tachyarrhythmias is available. An international registry is proposed as an important step toward obtaining the necessary data to develop evidence-based management strategies.