Method and device for the determining a maximum allowed velocity (V.sub.max) for a vehicle (1) when going downhill (2). The invention includes a detector (11) for detection of current inclination (alpha) of the vehicle (1) in relation to a horizontal plane (3), and means (10) for the determination of a value relating to the maximum allowed velocity (V.sub.max) of the vehicle in dependence of at least the value of the inclination (alpha). The invention also relates to a procedure for the control of the velocity. The invention provides a procedure for velocity control that takes the inclination into account when going downhill.