This paper presents a study of the behaviour of D-regions in reinforced concrete frames. Within the study, 12 twospan beams were tested to failure. The type of discontinuity imposed on the test beams reflects some common layouts that take place in nodes of actual reinforced concrete frames. The beams, 6 m long, were divided into two series (a first set had six beams with no crossing column and a second set had six beams with a crossing column at the inner support). The strength and the deformation capacity in beams with geometric discontinuities were studied as well as the influence of the column presence in the development of the plastic hinges. The main results are presented and discussed: evolution of the bending moment diagrams, moment-curvature relationships, plastic rotation behaviour, stiffness of the connection between the two spans and moment redistribution. As explained in the paper, the presence of a geometric discontinuity at the inner support region leads to a sharp decreasing of the ultimate moment at this region and consequently to a great decreasing of the ultimate load of the beam. Other consequences of having discontinuity in beams are explained. A strut-and-tie model was developed and presented. This model could be useful for the design D-regions.