Recent earthquakes have produced extensive damage in a large number of existing masonry buildings, demonstrating the need for retrofitting masonry structures. Externally bonded carbon fiber is a retrofitting technique that has been used to increase the strength of reinforced concrete elements. Sixteen full-scale shear dominant clay brick masonry walls, six with wire-steel shear reinforcement, were retrofitted with two configurations of externally bonded carbon fiber strips and subjected to shear loading. The results of the experimental program showed that the strength of the walls could be increased 13-84%, whereas, their displacement capacity increased 51-146%. This paper presents an analysis of the experimental results and simple equations to estimate the cracking load and the maximum shear strength of clay brick masonry walls, retrofitted with carbon fiber.