Doppler monitoring examinations were carried out during 67 simulated helium-oxygen dives in the pressure chambers of the Centre d'Etudes Hyperbares (CEH) COMEX Marseille, and involved a total of 232 COMEX professional divers. Three to five detections were done in each 24-h period, each consisting of an observation at rest and an observation after deep knee bends. Recordings of the Doppler signals were subsequently analyzed by experienced listeners and graded according to the system described by Spencer and Johanson (1974). The two vestibular decompression accidents in this series were associated with bubble scores of grade 3 at rest; one occurred during the rapid initial phase of a bounce dive decompression and the other after return to the storage depth after an excursion dive. Twenty-five cases of muscular or joint pains were observed. A higher incidence of this type of problem was found with higher bubble grades in general, although it was not possible to predict pain.