Animal experiments have demonstrated that the cholinergic system plays an important role in the activation of the cerebral cortex in conjunction with motor activities. In order to study the significance of the cholinergic system in the generation of voluntary movements in man, the effects of the anticholinergic drug biperidene on EEG states were analyzed. The effects depend strongly on the dosage and are shown in various frequency bands, topographic loci and time periods. Different functional significances of various frequency bands were found. In the alpha band motoric control processes are seen as an expression of mechanisms which substitute the cholinergic system. A shift of functions from the theta to the delta band with the increase of the medication seems to parallel an enhancement of motivational or volitional effort. The emergence of highly ordered EEG states is seen to be meaningful in view of the underlying processes of voluntary movements.