An important stage in designing of pieces made of composite materials consists of establishing the composite topology in such a way that it has certain properties needed in exploitation. The paper presents the mathematical apparatus and the calculation programme for establishing the optimum thickness of the composite groups so that it should have certain imposed (given) flexural stiffness. The method is applicable to all types of laminate composites, no matter of the cladding or matrix nature. The direct problem consists in determining the thickness of the groups and composite, minimising the bar mass, for an imposed (given) flexural stiffness, knowing the densities and elasticity modules of the groups. The indirect problem consists in determining the maximum stiffness, the thickness of the groups and composite for a given (imposed) mass, knowing the densities and elasticity modules of the groups. The presented programmes offer to the producer of this kind of materials the possibility to quickly establish the optimum topology.