REM sleep behaviour disorder (RBD) is characterized by savage extremities movements and by vocalizations associated with vivid dreams in REM sleep and by insufficient muscle atonia in REM sleep. Videopolysomnography was performed in nine patients (six men and three women, average age 59.8, SD +/- 7.2 years) suffering from Parkinson's disease (PD). The insufficient muscle atonia was found in the records of four subjects. No behavioural symptoms of RBD were observed. The authors stress on the disposition to RBD in great number of patients with RBD and on the necessity to look for RBD by detailed disease history.