A method for controlling driving on a hill of an all-wheel drive vehicle, wherein vehicle acceleration is determined and the gravitational acceleration is measured. To improve the accuracy of the determination of the vehicle reference speed in all-wheel drive vehicles, the method comprises the following steps: determining the acceleration at the secondary axle (Tc4wdHaAcc) from one or both of the two wheel speeds, determining the deviation (Slope) between the acceleration at the secondary axle (Tc4wdHaAcc) and the measured acceleration (LoSenAcc), filtering the determined deviation (SlopFilt) with a time constant (T1Slope), comparing the deviation (Slope) with the filtered deviation (SlopFilt), determining driving situations representing the conditions `traction slip control is active` or `traction slip control is not active`, and determining the slope in dependence on the comparison result and the driving situation.