Echography is an instrumental investigation that, availing of ultrasounds, provides images of internal organs and the various areas of the body. It is a diagnostic technique that has numerous specialist applications, in particular in gynaecology, obstetrics, orthopedics, urology, hepatology and gastrenterology. It is often the initial approach, with the clinical examination, to the majority of pathologies as quick and without any contraindications for the patient. In fact, the technological development of the machine has broadened its fields of interest: from the first gynaecological applications to nearly all specialities. Nowadays ultrasound scans are mainly used to investigate the liver, pancreas, spleen and kidneys, in obstetrics and gynaecology and vascular medicine (venous and arterial disorders). The doppler scan is the latest technological development as it is not limited to displaying internal organs but also provides information on the flow of blood through the arteries and veins and thus better study vascular disease, in particular stenoses. As regards the most recent applications, the endocavital technique is used, that is examining the prostate and pelvic organs through probes introduced internally thus providing a more precise and correct view. The latest developments in ultrasound study the articular and muscle-tendon structures: this more recent application is still in development. The use of the ecographic contrast agent, recently introduced, has further improved its diagnostic ability, especially in the field of oncology.