The climatic study undertaken in the prehistoric ornamented cave of Gargas at Aventignan, after the creation of a tunnel between two parts of the grotto, has permitted an underlining, thanks to the thermal studies of air and walls, and the circulation of air during different periods, the inconveniences which result. In these conditions, it was considered best to give up the initial project because the risks of drying and dehydration of the ornamented surfaces were prejudicial to their good conservation.