REM Behaviour Disorder (RBD) is a parasomnia which generally affects older age males, although either gender and all age groups may be affected. RBD presents as injurious behaviour to self and spouse or bizzare dream-enacting behaviour. It may emerge in the context of alcohol and drug abuse and withdrawal but it is generally chronic. RBD may be related with organic conditions like neurodegenerative diseases or naccolepsy. Frequently, this intresting disease may be the initial manifestation of parkinson disease and some other parkinsonian disorders. Most patients and their spouses report such recurrent behaviours like talking, laughing, yelling, swearing and kicking during sleep. These symptoms do not usually begin until approximately two hours after sleep onset. The frequency of RBD episodes can range from several episodes per night to one episode every two week. Clinical history is extremely important for diagnosis. Overnight polysomnographic monitoring with videoaping is necessary for the absolute diagnosis. Clonazepam is the drug of choice. Alternative therapies must be considered in patients not responding or tolerating clonazepam.