FM 96-5 Federico Bonetto, Giovanni Gallavotti, Pedro L. Garrido Chaotic principle: an experimental test The chaotic hypothesis discussed in [GC1] is tested experimentally in a simple conduction model. Besides a confirmation of the hypothesis predictions the results suggest the validity of the hypothesis in the much wider context in which, as the forcing strength grows, the attractor ceases to be an Anosov system and becomes an Axiom A attractor. A first test of the new predictions is also attempted. Keywords: Strange attractors, Chaoticity principle, Time reversal, TCP Fisica, Universita' di Roma La Sapienza, P.le Moro 2, 00185, Roma, Italia. e-mail bonetto@ipparco.roma1.infn.it giovanni@ipparco.roma1.infn.it garrido@gibbs.ugr.es tel. 39-6-49914370, fax 39-6-4957697