Abstract This paper presents a study on the efficacy of a shear strengthening technique utilizing fabric reinforced cementitious matrix (FRCM) systems for beams with and without internal transverse shear reinforcement (ITSR) within the critical shear span (CSS). The paper focuses on the FRCM/ITSR interaction, experimentally and analytically. Three different FRCM fabric types were used; namely, glass, carbon and polyparaphenylene benzobisoxazole (PBO). The test matrix consisted of fourteen medium-scale RC beams prepared and tested to fail in shear. The test results indicated a clear influence of the ITSR within the CSS on the gain in the ultimate load carrying capacity ( Pu ) of the beams. The FRCM strengthening system has enhanced the shear strength of the beams. With regard to the FRCM fabric type, carbon FRCM was the most effective of all in terms of the gain in Pu of the strengthened beams. Moreover, the beams strengthened with continuous strengthening configuration intuitively performed better than those strengthened with discontinuous configuration. A simplified compression field theory (SCFT) model was used for predicting the ultimate load carrying capacity of the beams. This model features two important contributions; namely, considering the effect of FRCM strengthening and accounting for the critical shear span to depth ratio.