Background: Dementia with Lewy bodies (DLB) is often associated with REM sleep behavior disorders (RBD) characterized, in contrast to the usual paralysis of REM sleep, by violent motor and verbal activity. Patients and Methods: The pharmacological management of RBD was investigated in three DLB patients treated with clonazepam, a benzodiazepine used as an antiepileptic, or donepezil, a cholinesterase inhibitor. Results: All three patients had marked improvement. The pharmacodynamic mechanisms underlying the efficacy of the two drugs might be due to facilitator effect on the pedunculopontine nucleus, a key structure in the physiology of REM sleep.