Transient bone marrow oedema syndrome of the proximal femur is characterized by acute, progressive pain in the hip that is increased by weight-bearing. Treatment includes restricted weight-bearing and analgesic medication. A prospective, randomized study was performed to compare two groups of patients affected by bone marrow oedema syndrome of the femoral head. 20 patients received pharmacological and hyperbaric oxygen therapy, and a control group of 21 patients received pharmacological therapy alone. The overall average WOMAC score at 3 months was significantly higher (p<0.001) for the hyperbaric oxygen group (70.8 points) compared with the control group (56.4 points). Magnetic Resonance Imaging at 3 months showed resolution of bone marrow oedema in 55.0% of the patients treated with hyperbaric oxygen compared with 28% in the control group. Hyperbaric oxygen therapy appears to be effective in treating transient bone marrow oedema syndrome, resulting in an accelerated recovery of hip function compared to pharmacological therapy alone.