The object of the invention is a method and an arrangement for modernizing an elevator group, in which method the elevators of the elevator group are modernized in turn such that both modernized elevators and unmodernized elevators can be simultaneously in use in the elevator group, of which elevators the modernized elevators are each provided with individualized identification marks while the old unmodernized elevators in use in the elevator group are each provided with a similar identification mark to each other.