The aim of this paper is to highlight coronary investigation by transthoracic Doppler evaluation. This application has recently been introduced into clinical practice and has received enthusiastic feedback in terms of coronary flow reserve evaluation on left anterior coronary artery disease diagnosis. Such diagnosis represents the most important clinical application but has in itself some limitations regarding anatomical and technological knowledge. The purpose of this paper is to offer a didactic approach on how to investigate the different segments of left anterior and posterior descending coronary arteries by transthoracic ultrasound using different anatomical key structures as markers. We will conclude by underlining that, nowadays, innovative technology allows complete evaluation of both major coronary arteries in many patients in a resting condition as well as during pharmacology stress-tests, but we often do not know it.