Hyperbaric oxygen therapy (HBOT) involves inhalation of 100% oxygen at supra-atmospheric ambient pressure. HBOT is used as either a primary or adjunctive treatment in the management of infections such as gas gangrene, necrotizing fasciitis, diabetic foot infections, refractory osteomyelitis, neurosurgical infections and fungal infections. HBOT acts as a bactericidal/bacteriostatic agent against anerobic bacteria by increasing the formation of free oxygen radicals. HBOT restores the bacterial-killing capacity of leukocytes in hypoxic wounds by increasing tissue oxygen tensions. In addition, HBOT acts synergistically with a number of antibiotics. This article reviews the anti-infective effects of HBOT and the use of HBOT in the treatment of certain infectious diseases.