Abstract: Elementary results obtained by energy method are applied to the buckling of stitched laminates and woven composites with three-dimensional (3D) reinforcement that contain circular delamination cracks. The through-thickness fibers are assumed to provide continuous, linear restoring traction's opposing the deflection of the delaminated layer adjacent to the crack. With the boundary condition that the ends of the delaminated layer are clamped and with deflections permitted in one direction only, there exists a characteristic length a₀ for buckling: if the radius, a, of the circular delamination crack exceeds a₀, then. when buckling occurs, it will be only within subregion r/0,and will usually not span the whole delamination: if a does not exceed a₀, the bucking will span the whole region(r