This paper presents a theoretical investigation into the scattering of a Rayleigh wave by a surface-breaking crack subjected to a compressive stress. The boundary conditions at the partially contacting crack surfaces are modelled according to the quasi-static approximation. Following the results of recent investigations on the subject, the ratio between in transverse and the normal stiffness constants of two rough surfaces in contact is assumed to be 0.55. The model allows for arbitrary distributions of the interfacial stiffness constants in order to simulate the effect of applied compressive stress fields having arbitrary shape along the crack faces. Results are presented to illustrate the behavior of the reflection and transmission coefficients, as well as the dependence of the total energy radiated into the bulk, as functions of a) the ratio between the crack depth and the Rayleigh wavelength, and b) the interfacial stiffness constants. At high frequency, the model predicts an surprising initial increase of the reflection coefficient as the interface stiffness increases, followed by the expected decrease below the value typical of an open crack. It is also shown that the relative variation of reflection coefficient from cracks having the same interfacial stiffness depends on the depth-to-wavelength ratio.—This work was funded by the 5thFramework Program of the European Commission. ©2000 American Institute of Physics.