A simple and reliable process for activating a medical instrument, for example, one containing an anesthetic agent- or drug-dispensing unit (23) as well as a respirator drive (24) for respirating a patient is provided. The medical instrument is switched on, and a sensor (20) for detecting biometric features of a user, which is connected to or communicates with the medical instrument, is activated by the switching on, so that the individual biometric features of a certain user are detected. Te detected individual biometric features of the certain user are compared with the biometric features of at least one user within a preset time period. The medical instrument is released for the operation by the certain user only in case of agreement between the detected individual biometric features of the certain user and biometric features of at least one user, which were entered in the memory in advance.