Rapid eye movement sleep behavior disorder (RBD) is a parasomnia in which there is enactment, often violent, of dream mentation. Although this syndrome is sometimes associated with neurologic disorders, psychiatric comorbidity is not typical. The authors present a unique series of veterans with RBD. A high incidence of comorbidity with post-traumatic stress disorder is noted. The literature on RBD is reviewed, and the coexistence of RBD and post-traumatic stress disorder is reasoned. The authors suggest that it is possible that similar neuropathologic processes are responsible for both conditions, at times in the same patient.