Ultrasound is a simple, non invasive and accessible imaging technique that allows the evaluation of the musculoskeletal system in real time, with the advantage of examining the joints in a dynamic way and with the aid of Doppler power, local inflammatory phenomena can be evaluated, without submitting the patient to radiation. It has the disadvantage of being operator dependant, which has to have a wide knowledge of the physical principles of ultrasonography, has to be familiar with the sonographic anatomy and musculoskeletal anatomy, but even more it is important that he has the ability to recognize the sonographic phenomena that can present as decoys, nominated artifacts. This knowledge is desirable to the specialist in musculoskeletal conditions, so that ecographic studies can be interpreted and recognizing artifacts and avoiding wrong diagnosis and unnecessary procedures. In the present review, the basic principles of ecography are analyzed, the normal sonographic anatomy of the musculoskeletal system ant the more common artifacts encountered in ecography.