Vinyl chloride is a gas with a boiling point of -18[degree]C. It is soluble in ethereal solvents, and its vapors are combustible. It was suggested as an anesthetic by Patty and was tried on humans by Schaumann. They found its action to be similar to that of ethyl chloride and less toxic than CHCI3 or CCI4. The anesthetic limiting cone, is between 7 and 10 vol.%; 12 vol.% is dangerous. Despite the fact that it is less saturated, it is less potent than C2H5CI. The anesthetic blood cone, with both gases is about 20 mg. %. Three dogs were anesthetized with vinyl chloride. In two, a 50 vol.%, and in one a 25 vol.% cone, was used for induction; then the cone, was reduced to 7 vol.%. Induction was rapid, there was continuous "crowing", and increased salivation. Abdominal relaxation was good, but legs were rigid and showed incoordinated movements throughout the anesthesia. Recovery was prompt, but accompanied by violent excitation. In 4 dogs, the femoral artery was cannulated under local anesthesia, and then the animals were anesthe-tized with 10 vol.% vinyl chloride. There was no change in blood pressure throughout the anesthesia, but definite cardiac irregularities developed. These irregularities disappeared when the anesthetic was changed to ether. These cardiac irregularities were confirmed by ECG tracings in 6 dogs anesthe-tized to various depths with vinyl chloride. These findings indicate that vinyl chloride is a potentially dangerous agent, and its use in man is unwarranted.