Laminate composite materials are widely used in aerospace, wind energy and marine industries as they provide a good strength to weight ratio and allow for unique structural design. However, in-service impacts can cause barely visible damages such as specific to composites delaminations, which reduce the load-bearing capacity of the structure. Damage detection and characterization could be achieved with nondestructive testing and structural health monitoring methods physically based on elastic guided waves. Their efficiency can be enhanced by preliminary numerical modeling of the ultrasonic wave interaction with a delamination-type damage, which enables a deeper understanding of the corresponding wave phenomena.In the current paper, this problem is addressed using the boundary integral equation method, which involves discretization of only the damage boundary, thus minimizing the requirements on computational resources. The scattering of fundamental Lamb waves by a rectangular delamination in anisotropic unidirectional and cross-ply laminates is considered as an example, and the results obtained are verified by comparing with 3D finite element-based predictions.