Abstract: An ultrasound transducer for diagnostic and therapeutic generates ultrasound waves of different wavelengths in diagnostics mode or therapy mode. The ultrasound transducer has an n.times..lambda./4 matching layer for a propagation medium adjoining the ultrasound transducer, and a piezoelectric ultrasound transducer element with a first electrode located between the matching layer and the ultrasound transducer element, a second electrode attached at the opposite side of the ultrasound transducer element, and a third electrode that divides the ultrasound transducer element into two regions. Ultrasound waves can be generated for the diagnostics mode and for the therapy mode dependent on the division of the ultrasound transducer element. The n.times..lambda./4 matching layer is effective for the wavelength of the ultrasound waves in diagnostics mode as well as in therapy mode.