Rapid-eye-movement (REM) sleep behavior (RBD) is a form of REM sleep motor dyscontrol characterized by complex, vigorous, and frequently violent behaviors without atonia during the REM sleep. The motor dyscontrol may include not only cataplexy and sleep paralysis but alto periodic limb movements during REM and non-REM sleep. We examined two patients with charateristic episodes of behavioral manifestations during the REM sleep as well as with other sleep disorders such as narcolepsy and periodic limb movement disorder. The one patina was an 18 year-old man who had childhood-onset RBD associated with narcolepsy since 10 years old. The polysomnographic studies showed excessive augmentation of chin EMG and 6 attacks of violent behavior during REM sleep. He also complained of cataplexic symptomes. Multiple sleep latency tests (MSLT) showed four sleep onset REMs and two episodes of violent behavior during the REM sleep. The other patient was a 74 year-old man who complained of violent behaviors during the REM sleep and polysomnographic studies showed excessive augmentation of chin EMG during the REM sleep and periodic leg movements for 24min. And 14sec. During the sleep. We report two patients with RBD which were associated with narcolepsy, and periodic limb movememt disorder irrespectively, suggesting that RBD, narcolepsy and periodic limb movement disorder could occur coincidently and be understood as a motor dyscontrol during REM sleep.