TRIFLUOROETHYL VINYL ETHER (Fluoromar) is a promising new gaseous anesthetic agent which is virtually noninflammable and produces minimal gastrointestinal irritation. The effects of this agent on cardiac output have not been previously reported. Therefore, in this investigation the effects of this agent on the cardiovascular system, and in particular on the cardiac output, were studied and compared with values obtained with halothane (Fluothane). Ten healthy volunteers, 22 to 38 years of age, were the subjects. Following a 16-hour fast, the group was studied ( a ) while awake, ( b ) during trifluoroethyl vinyl ether anesthesia, and (c) during halothane anesthesia; each was maintained at electroencephalogram (EEG) level 4, as reported by Mayo, Bickford, and Faulconer. Intravenously, 0.3 to 0.4 mg. of scopolamine or atropine was given. No opiates, barbiturates, or tranquilizing agents were used. During each of the study periods, cardiac output was measured in duplicate by the indicator-dilution