High resolution ultrasound (HRUS) has been used in the assessment of knee pathology for a few decades. However, its role as a valid imaging tool still needs to be determined. The specific scanning methods, different types of lesion, and operator dependence might account for the variation in its reported efficacy in different studies. Some clinicians use HRUS as a first-line imaging modality to detect soft tissue injury of the knee; however, others have questioned its accuracy. HRUS can detect lesions of the suprapatellar recess, patellar tendon, medial and lateral collateral ligaments, medial and lateral menisci, and posterior cruciate ligaments. This article describes common pathologies of the knee, discusses the efficacy of sonographic examination, and outlines its clinical applications.