Objective: The present study examined sleep-related problems (SRPs) among a large sample (n = 128) of youth with anxiety disorders (i.e., generalized, separation, and social). The frequency of eight specific SRPs was examined in relation to age, gender, type of anxiety disorder, anxiety severity, and functional impairment. The impact of pharmacological treatment (fluvoxamine versus pill placebo) in reducing SRPs also was examined. Method: As part of a large, double-blind, randomized, controlled trial (Research Units on Pediatric Psychopharmacology Anxiety Study Group), clinician and parent reports of SRPs were examined among children and adolescents, ages 6 to 17 years, before and after treatment. Results: Eighty-eight percent of youth experienced at least one SRP, and a majority (55%) experienced three or more. Total SRPs were positively associated with anxiety severity and interference in family functioning. Significantly greater reductions in SRPs were found among children treated with fluvoxamine compared with placebo. Conclusions: These findings indicate that SRPs are commonly associated with childhood anxiety disorders and suggest a need for the assessment of and attention to these problems in research and clinical settings. (Contains 5 tables.)