This study discusses the dispersion equation for SH waves in a non-homogeneous monoclinic layer over a semi-infinite isotropic medium. The wave velocity equation has been obtained. In the isotropic case, when the non-homogeneity is absent, the dispersion equation reduces to a standard SH wave equation. The dispersion curves are depicted by means of graphs for different values of non-homogeneity parameters for the layer and semi-infinite medium.