Of 34 hospitalized patients receiving low flow oxygen (1 to 4 l/min) continuously by nasal cannula, 19 randomly selected patients breathed humidified oxygen and 15 randomly selected patients breathed dry oxygen. During a 5- to 10-day study period the patients answered questions about subjective findings of dry nasal passages, dry throat, headache, chest discomfort, cold symptoms, and changes in sputum production. No significant difference was found in any of these complications between the patient group breathing humidified oxygen and the group breathing dry oxygen. Because of the apparent lack of problems attributable to inhalation of dry low flow oxygen, and because of the cost of humidifying low flow nasal oxygen, our hospital has discontinued humidifying oxygen administered in this way.