The effect of two drugs upon multifocal myoclonic jerks was evaluated. The drugs influence the central cholinergic system in opposite ways. Eight patients with progressive and nonprogressive myoclonic epilepsy were tested. The single blind test was used. The number of myoclonic jerks after intravenous physostigmine (mean dose 0.02 mg/kg) and that after atropine (0.04 mg/kg) was compared to number of myoclonic jerks in the drug-free periods and with placebo. Placebo was without an effect. Physostigmine slightly increased the number of jerks. Atropine decreased the number significantly. In most patients the results were not striking. It is suggested that the cholinergic system may participate in the physiopathology of the studied myoclonic in a rather indirect, perhaps modulating way.