A method of regulating fiber quantities supplied to a fiber processing machine of a fiber processing line. The latter includes a fiber storing apparatus connected downstream of the fiber processing machine and receives processed fiber therefrom. The fiber processing machine includes a feed roller supplying fiber thereto. The method comprises the following steps: continuously rotating the feed roller by a regulatable drive during operation of the fiber processing line; generating a measuring value representing momentary fiber quantities in the storing apparatus; generating an analog electric signal representing the measuring value; and applying the analog electric signal to the regulatable drive of the feed roller for varying the rpm thereof as a function of the fiber quantity in the storing apparatus.