The invention is directed to a method for controlling the lambda value of the air/fuel mixture supplied to an internal combustion engine. The method utilizes the signal of a lambda probe as the measurement of an actual value with this actual value displaying discontinuities during the transistion from the rich to the lean lambda region. The switch-over of the control direction in the direction "rich" is undertaken when the actual value in the form of the probe voltage passes through the reference voltage; however, this only happens when the probe voltage had an previously climbed to a threshold value "rich". Correspondingly, the control direction is swiched over to the direction "lean" only when the reference value is passed through and when the probe voltage previously had dropped to a threshold voltage "lean". The apparatus which operates pursusant to the method no longer leads to undefined control oscillations when cylinder scatter effects occur.