Pathophysiologic mechanisms involved in the application of HBO therapy are poorly understood that may limit its clinical use. However, useful indications are well standardized in the setting of critical care medicine, CO poisoning, decompression sickness, gas gangrene and soft tissue anaerobic infections, crush syndrome, burns, sudden deafness... HBO therapy is also indicated in the management of chronic limb ischemia, diabetic foot lesion, osteomyelitis, osteoradionecrosis. These clinical indications have been evaluated in a Consensus Conference on Hyperbaric Medicine that has classified its application according to its efficiency. Indications were classified as strongly recommended (positively affects the patient's survival), recommended (does not influence the patient's survival but is important for the prevention of serious disorders) and optional (regarded as a additional treatment modality). Clinical application of HBO therapy requires specific equipment including a multiplace hyperbaric chamber and specific educational program and training for personnel employed in the clinical hyperbaric center. Lastly, HBO therapy is related to accurate rules defining its indications as well as its evaluation that are minimal prerequisites for safety and clinical results.