In the last decade there has been an increase in the incidence of decompression sickness in Ireland. The modern diver, equipped with specially developed diving equipment, is exposed to abnormal physiological conditions. This has resulted in a spectrum of medical conditions, which need to be recognised, diagnosed and treated. The department of Underwater Medicine at University College Hospital, Galway, is the only referral centre in the Republic of Ireland for patients suffering from decompression sickness. Early recognition and referral for treatment dramatically improves patient outcome. A one year's review of patients referred for treatment is presented.