Objective: To determine whether parents' observation, clinical examination, and lateral upper airway radiograph are useful in detecting clinically significant obstructive sleep apnea (OSA) in children. Method: We retrospectively reviewed data of 50 children aged 4 to 18 years who were consecutively referred to a sleep clinic for suspected OSA. All subjects underwent clinical assessments including standardized history collection, physical examination, and lateral neck radiograph for measurement of postnasal space. Each child underwent overnight polysomnography on the night of clinical assessments. Patients with clinically significant OSA, defined as apnea-hypopnea index (AHI) > 5, were compared with primary snorers, defined as AHI <= 5. Results: Thirty-one children had clinically significant OSA, and 19 children were primary snorers. The prevalence of risk factors including allergic rhinitis, obesity, and craniofacial anomaly was similar between the two groups. Observable apnea during sleep, nocturnal enuresis, intrusive naps, Mouth breathing, enlarged tonsils, and radiologic features of upper airway narrowing due to adenoid hypertrophy were found to be predictors for, clinically significant OSA. Combining upper airway narrowing and mouth breathing or nocturnal enuresis bad a sensitivity of 90.3%, and combining all six predictors had a sensitivity of 93.5% of detecting OSA. Conclusion: Combining clinical and radiologic bindings might be helpful to screen for children with clinically significant OSA who need earlier investigation and intervention.