A device and method for guiding surgical tools by ultrasonic imaging having means for acquiring a time sequence of 3D ultrasonic images of a target area, means for determining and tracking the position and orientation of a surgical tool and means for defining the direction of a characteristic axis of the tool corresponding to the detected position and orientation of the tool. The device further having means for determining the position of a working end of the tool along the characteristic axis, means for determining the relative position in space of each 3D image and the direction of the characteristic axis corresponding to each 3D image, and means for generating a 2D image defined by an image plane that intersects the corresponding 3D image of said time sequence.
