Two groups of 8 monkeys were anesthetized with either BAX-3224, a new fluorinated methyl-propyl ether, or with halothane, 3 hours daily for a total of 30 hours. Vomiting incidence was 12.5 percent with BAX-3224 during both induction and recovery, compared with 3.7 percent for halothane during induction and 7 percent for halothane during recovery. Induction time did not change during the course of study with either agent. Respiration was spontaneous and cardiopulmonary function was stable. Electroretinographic (ERG) responses were consistent, flicker-light responses similar, but visual evoked responses (VER) were not present during BAX-3224 anesthesia. A 33 percent incidence of electroencephalographic (EEG) silence occurred with BAX-3224, which was consistent with absence of VER. Hematologic and serum chemistry values were similar for both agents. Serum fluoride ion concentrations, measured before exposure and 4 times during the 10-day study, did not change after administration of either agent. This finding was significant for BAX-3224, a fluorinated ether. No cardiac arrhythmias were observed during BAX-3224 anesthesia, compared with a 17 percent incidence during halothane induction. Recovery time was 32 minutes following BAX-3224 and 14 minutes after halothane. BAX-3224 produced anesthesia similar to that of halothane, did not induce changes incompatible with recovery from anesthesia, and showed great potential as a new volatile liquid anesthetic agent with excellent biologic stability.