The paper deals with the laboratory tests on timber-steel-concrete composite beams, equipped with an innovative connection system. Tests are part of a more comprehensive experimental campaign, aiming at the evaluation and optimization of the connection devices. In this paper both monotonic and cyclic bending tests on six composite beams are presented. In particular, each specimen consists of a timber beam with rectangular cross section, connected to a concrete reinforced slab by means of steel collars. Specimens differ for the type of collar-timber contact and the collars spacing, in order to determine the more effective solution. The system performance has been evaluated in terms of both maximum force-displacement relationship and accumulated dissipated energy at failure. © 2008 Taylor & Francis Group, London.