Ten patients with status asthmaticus and respiratory or combined respiratory and metabolic acidosis were treated with a mixture of helium-oxygen (He-O2) in addition to the usual bronchodilator therapy and corticosteroids. A significant reversal of the acidosis was noted within the first 20 minutes, and no patient required subsequent intubation. The He-O2 mixture was started after the aerosolized and subcutaneous bronchodilators, but before intravenous corticosteroids and aminophylline had reached their peak effects. There were no untoward reactions and most of the patients sensed an immediate reduction in their dyspnea with the onset of He-O2 therapy. We conclude that He-O2 may be a useful adjunct to the usual medications employed in the treatment of status asthmaticus and may allow some patients to avoid intubation and mechanical ventilation.