['The objective of this study was to examine the relationship of obstructive sleep apnea (OSA), body weight (BMI percentage [BMI%]), and monosymptomatic nocturnal enuresis (MNE) in children.', 'A case-control study design was used. All children were 5 to 15 years of age; case patients were recruited from a comprehensive sleep disorders center (n = 149), and control subjects were recruited from a general pediatric practice in the same catchment area (n = 139). Case patients were subject to overnight polysomnograms and grouped into apnea severity categories (minimal, mild, moderate, or severe) on the basis of respiratory disturbance index and minimum arterial oxygen saturation levels. Data for all children included age; gender; height; weight; and history of MNE, snoring, diabetes, nasal allergies, and/or enlarged tonsils. BMI% was used to group children into weight categories as suggested by the Centers for Disease Control and Prevention (underweight, normal weight, at risk for overweight, and overweight). Two age groupings were created (5-10 years and 11-15 years). Descriptive statistics provided the prevalence of OSA, weight category, and MNE among case patients and control subjects. Cross-tabulations examined the relationship of severity of OSA with weight categories and MNE, stratified by age and gender. A series of logistic regression models explored the interrelationship of the grouping variables.', 'A large majority (79.9%) of control subjects were at risk for overweight, and a large majority (80.0%) of children with MNE also had some degree of OSA. Logistic regression demonstrated that both MNE (odds ratio: 5.29) and overweight (odds ratio 4.16) were significantly associated with OSA but not with each other.'] Are nocturnal enuresis and overweight associated with obstructive sleep apnea?