To further improve, under ultrasonic observation, the visibility of a medical instrument with at least one portion of the instrument that can be inserted into body tissue of a patient and has a surface structure reflecting ultrasound waves, wherein the surface structure comprises a number of reflection elements, it is proposed that at least three, and at most nine, reflection elements which are arranged in a defined way in relation to one another define a reflection element group and that the surface structure comprises at least two reflection element groups.
