Abstract: A vaporizer interlock system is disclosed which is used in an anesthesia machine having two calibrated vaporizers for providing an anesthetic to a patient and further having a selector valve with three positions, two extreme positions where one of the two vaporizers is being utilized and a middle position where neither vaporizer is used. The system prevents opening of either vaporizer when the selector valve is in the middle position. Also, when the selector valve is moved to one of its extreme positions selecting one of the vaporizers, the other vaporizer is prevented from being moved from its "off" position. The "on" vaporizer must thereafter be placed in its "off" position before the selector valve can be returned to its middle position. In addition, a quick disconnect means is shown for quickly attaching and detaching the vaporizers from the anesthesia machine.