Abstract: An anesthetic vaporizer 1 for use particularly with anesthetic agents having a low boiling point comprises an inlet 2 for carrier gas an an outlet 4 for carrier gas and gaseous anesthetic agents. A first passage 6 extends between the inlet 2 and the outlet 4. A flow restrictor 8 is located within the passage 6. A second passage 10 extends between the first passage 6 at a location upstream of the flow restrictor 8 and a regulator 14. The regulator 14 controls the pressure of gaseous anesthetic agent when flowing through a third passage 26 extending from a vaporizing chamber 12 containing anesthetic agent to the first passage 6 at a location downstream of the flow restrictor 8. A flow control valve 28 is located in the third passage 26.