We report a 69 years old male with a parkinsonian syndrome and a 50 years o
ld female without neurological problems who showed violent behavior during
REM sleep. Polysomnography showed that both had tonic or phasic muscular ac
tivity during REM sleep and a REM sleep behavior disorder was diagnosed. Cl
onazepam was used in both, with good clinical response. This condition is f
requently unrecognized and confused with nightmares, nocturnal delirium or
other parasomnias.