Study Objectives: In this study, we investigated the prevalence of symptoms of restless legs syndrome (RLS) in biological caregivers of children with a diagnosis of autism spectrum disorder (ASD).The relationship of RLS symptoms to caregiver health-related quality of life (HRQoL) was also examined. Finally, we compared the sleep quality and daytime behaviors of children with ASD in caregivers with and without symptoms of RLS. Methods: Biological caregivers (n = 50) of children ages 6 to 11 y with a diagnosis of ASD completed a Sleep Habits Questionnaire (SHQ) that included RLS as determined by four questions. HRQoL was assessed using the Medical Outcomes Survey (MOS) 12-Item Short Form (SF-12). Caregivers also completed the Children's Sleep Habits Questionnaire (CSHQ) and Child Behavior Checklist (CBCL6/18). Results: Eleven caregivers (22%) fit the criteria for RLS symptomatology and caregivers with RLS reported poorer mental health. Caregivers with RLS described more night waking and greater internalized behavior problems in their children with ASD than the caregivers without RLS. Conclusions: Biological caregivers of children with ASD demonstrated a high prevalence of RLS symptoms and poorer mental health. RLS is known as a sleep disorder that has strong heritability, and it is possible that many of the children with ASD also have symptoms of RLS. RLS as a possible disruptor of sleep should be considered in caregivers and in their children with ASD. Keywords: autism spectrum disorder, caregivers, health-related quality of life, restless legs syndrome Citation: Russell M, Baldwin C, McClain D, Matthews N, Smith C, Quan SF. Symptoms of restless legs syndrome in biological caregivers of children with autism spectrum disorders.