In this study, a dynamic TV pupillometric system has been used to record the effects of the anticholinergic drug biperidene (Akineton) on pupil responsiveness to various types of stimuli. Plasma levels of the drug were evaluated by means of the radioreceptor binding technique at the same times of pupillometric monitoring. An excellent correlation was found between the effects of biperidene on pupil diameter after light and dark adaptation, light reflex and near vision reaction and the plasma levels of the drug. Radioreceptor binding and dynamic TV pupillometry represent useful tools to evaluate the possible alterations induced by drug therapy on the cholinergic system in man.