An ultrasound probe for three-dimensional scanning and focusing of an ultrasound beam in both an azimuth direction and an elevation direction normal to the azimuth direction. The probe is composed of an ultrasound transducer array which has a linear division of the elements in the azimuth direction for electronic steering of the beam direction and focus in the azimuth direction. The array elements have a coarse division in the elevation direction for electronic steering of the focus in the elevation direction, and possibly small angle direction steering of the beam in the elevation direction for parallel receive and/or transmit beams. Large angle direction scanning of the beam in the elevation direction is obtained by mechanical rotation of the array around an axis. The invention implies useful embodiments for insertion of the probe into the body, through mounting the array at the distal tip of an elongated device.