The directivity patterns of angle probes commonly used in ultrasonic material-testing are studied both theoretically and experimentally. Expressions are obtained for longitudinal waves and transverse waves radiating into the body under test and for surface waves propagating over the surface of the body, treated as a semi-infinite isotropic medium. Numerical computations are given in all three cases for a steel object. The theoretical deductions are partially checked by experiments for the case of longitudinal and surface waves. Some problems to be considered in ultrasonic testing are pointed out.