A process is provided for controlling at least one parameter of the breathing gas supply of a respirator with a patient connected to it as well as to a corresponding control device. The respiration pressure, the breathing gas flow generated by the respirator as well as the respiration rate may be used as parameters. The process presents the advantage that the control of the current respiration needs of the patient are taken into account by the muscle pressure (PMUS), i.e., the percentage of the airway pressure caused by the patient's own effort, being maintained at a value close to zero. An airway pressure (PAWC) is first calculated for this purpose from previously measured values for the airway pressure (PAW) and the breathing gas flow (d/dt V) and the mechanical parameters resistance (RL) and compliance (C) of the patient's lungs, which were determined therefrom, and this is subsequently compared with the actually measured value for the airway pressure (PAW). The at least one parameter of the breathing gas supply of the respirator is subsequently controlled on the basis of the comparison between PAWC and PAW, expressed as the muscle pressure PMUS=PAWC−PAW.