In 2019, "The Lisbon Agreement on Femoroacetabular Impingement Imaging" project was born with the aim of finding an unambiguous agreement regarding imaging for FAI. It was determined that anteroposterior and lateral radiographs represent the minimum protocol, and that Dunn view at 45° is the most appropriate to identify a CAM alteration. Instead, for PINCER abnormalities, the presence of protrusio acetabuli, cross over sign, posterior wall sign, ischial spine sign, center edge angle and cranial acetabular version are considered, which can be obtained from AP Rx, CT scan and NMR. In addition to defining which diagnostic criteria are to be taken as a reference, the importance of an accurate differential diagnosis is emphasized when evaluating a subject who among various hypotheses may raise that of FAIS. Systematic reviews identify that the various clinical diagnostic procedures are more reliable in excluding than including FAIS. The authors of the most recent (2022) systematic review on the diagnostic accuracy of clinical tests dedicated to FAIS, assert that there are no single tests that can allow rule in of a CAM or mixed-type FAI, while FADIR, FPAW and maximal squat could be combined to rule out CAM or mixed-type FAI.