The European Association for Cardiovascular Imaging (EACVI) has outlined the rationale for setting appropriate use criteria (AUC) in cardiovascular (CV) imaging. Transthoracic echocardiography (TTE) is the most common imaging modality in CV disease and is a central tool in diagnosis, follow-up, management planning and intervention. The purpose of AUC is to inform referrers, both to avoid under-use, which may result in incomplete or incorrect diagnosis and treatment, and also over-use, which may delay correct diagnosis, lead to 'treatment cascade', and wastes resources. The first step in defining AUC for TTE in the adult has been for a panel of experts in echocardiography to review the evidence, guidelines, recommendations, and position papers from the European Society of Cardiology, EACVI and other specialist societies, and current state-of-the-art clinical practice. The attached document summarizes this work, which will be used to under-pin the development of AUC.