The authors have examined the pH, the pCO2, the pO2, and the oxygen saturation of the blood of patients upon whom endonasal surgery followed by tamponing of the nose had been performed. The gas values were examined on the second postoperative day and two days after the tampons had been removed. It was found that the blood pH remained within normal limits, whereas during the acute obstruction the pO2 values were diminished, the pCO2 values were increased, and the oxygen saturation of the blood was noticeably diminished. The authors recommend carefulness if the noses of patients with cardiorespiratory insufficiency are to be tamponed.