Abstract: Material degradation is usually preceded by some kind ofnonlinear mechanical behavior before significant plastic deformation ormaterial damage occurs. When an ultrasonic wave propagates through thematerial at this stage, a strong nonlinear effect will be generated and thushigher harmonics will be produced due to the nonlinear elastic properties ofthat material. In this paper, advances in experimental and theoreticalstudies of nondestructive test and evaluation (NDT and NDE) of materialdegradation under fatigue, tension and creep loads using nonlinearultrasonic waves were reviewed, including advances in experimental andtheoretical studies of NDT and NDE of bond strength and mechanicaldegradation of adhesive joints. Also, further studies in the field of NDTand NDE using nonlinear ultrasound were suggested.