Rapid eye movement (REM) sleep behavior disorder (RBD) has a reported male predominance. This gender difference may partially relate to underdiagnosis of RBD in women. Less violent behaviors, decreased numbers of behaviors on sleep studies, genetics, risk of neurodegenerative disorders, age, hormones, and lack of bed partner may contribute to this gender difference. As more evidence accumulates supporting idiopathic RBD as an early manifestation of a neurodegenerative disorder such as Parkinson’s disease, it is imperative to fully recognize RBD in both genders.