An apparatus specifìcally designed for static and cyclic testing of concrete and rock cylindrical samples is described. A particular characteristic of this equipment is the possibility of cyclic variation of the confining pressure, in addition to variation of the vertical load. The technical features of the apparatus are illustrated, as well as those of the instruments used for measuring and recording the variation of loads and displacements during the tests, up to the failure of the specimens. Comments are also presented on the devices controlling the variation of load with time and on the characteristics of the load histories adopted in an experimental research aimed at investigating the behaviour of concrete under repeated triaxial loads.