Composite materials are widely used for strengthening existing masonry structures and improving their seismic performance. The present paper investigates the behaviour of masonry walls subjected to in-plane load and externally strengthened by different kinds of composite materials, as no-well established formulation has been still found to predict the real contribute of the external fiber reinforcement to the shear strength of masonry walls. In this paper a brief review of analytical formulae available in the scientific literature is firstly here presented. Secondly the mentioned models are assessed by means of a wide database collecting experimental results of tests on masonry wall.