New tests of the vestibular function have been developed. They should help to explain some clinical situations. The paper describes 3 tests today used routinely in most centers, with a special emphasis on the sign of Halmagyi, or head impulse test. It is designed to detect deficits of the semicircular canal function in the horizontal and vertical directions as well. It is feasible without any equipment. However, an infrared camera connected to a computer increases markedly its sensitivity.