Abstract: A mixture control for an internal combustion engine with a lambda probe and with a memory device containing nominal values for the fuel supply dependent on operational values of the engine, as load, rotational speed and temperature. The mixture control renders it possible to optimize the consumption and/or emission, under consideration of the operating conditions, in the entire moving range of an internal combustion engine. The memory device comprises address positions selectable by the operating values of the internal combustion engine and also by the actual lambda value, and stores nominal values for the fuel supply in the form of a map for a characteristic field. The probe voltage and the internal resistance of the lambda probe are determined.