A control device for anesthetic vaporizers disclosed herein ensures that the operator is able to select a desired anesthetic with certainty, and to assure that other anesthetic vaporizer apparatus also in use is in an "off" condition when one anesthetic has been selected. The apparatus also includes a setting at which all of a plurality of associated anesthetic vaporizers are safely "off". The invention comprises a rotatable rod adapted for mounting on an assembly of anesthetic vaporizer tanks, the rod having a plurality of C-collars thereon, the opening in each C-collar adapted to receive a flat spiral wing projecting from the on/off control on an anesthetic vaporizer. The C-collars also permit a setting at which it is impossible to open any of the associated anesthetic vaporizers. The control mechanism includes visual indicia as well as an audible indicator when a correct setting has been selected by the operator.