Abstract. The propagation of nonlinear elastic anti-plane shear waves in a unidirectional fibre-reinforced composite material is studied. A model of structural nonlinearity is considered, for which the nonlinear behaviour of the composite solid is caused by imperfect bonding at the "fibre-matrix" interface. A macroscopic wave equation accounting for the effects of nonlinearity and dispersion is derived using the higher-order asymptotic homogenization method.Explicit analytical solutions for stationary nonlinear strain waves are obtained.This type of nonlinearity has a crucial influence on the wave propagation mode: for soft nonlinearity, localised shock (kink) waves are developed, while for hard nonlinearity localised bell-shaped waves appear. Numerical results are presented and the areas of practical applicability of linear and nonlinear, long-and shortwave approaches discussed.