We consider the phenomenon of back reflection of a beam of ultrasound from a liquid–solid interface. We show that the magnitude of the back reflection depends critically upon the profile of the incident beam. The beam profile is first related to the excitation field at the plane of the transducer. Different beams are considered by changing the field at the transducer. We show that a purely Gaussian profile gives no back reflection. Other beam profiles with less severe decay away from the beam center can produce an effect of the same order as observed experimentally. We present an example of such a beam.