to obtain the OSAS prevalence and risk factors of OSAS in obese early adolescents and to create a scoring system based on risk factors for diagnosing OSAS. an observational study in Jakarta, November 2007 until December 2008 on obese adolescents aged 10-12 years with snoring. Subjects underwent clinical examination, lung function test, paranasal sinus X-ray, and polisomnography. Measured outcomes were diagnosis of OSAS; sensitivity, specificity, predictive values, and likelihood ratios of a scoring system based on risk factors. the prevalence of OSAS in obese early adolescents is 38.2% using AHI cut-off point of> 3 on PSG. Tonsillar hypertrophy, adenoid hypertrophy, and neck circumference were the main risk factors. Scoring system was designed based on these results: OS= T+ A+ NC; OS= OSAS score; T= tonsil hypertrophy (> T3 scored 1,< T3 scored 0); A= adenoid hypertrophy (adenoid and nasopharynx ratio of> 0.8 scored 1.5,< 0.8 scored 0); NC= neck circumference (> 34 cm scored 1;< 34 cm scored 0). Children were most likely to have OSAS if they had a total score of 3.5. This scoring system has a sensitivity of 62%(95% CI 47 to 77%), specificity 100%(95% CI 100 to 100%), positive predictive value 100%(95% CI 100 to 100%), negative predictive value 81%(95% CI 73 to 89%), unlimited LR (+), LR (-) of 0.38 (CI 95% 0.6 to 0.56). a scoring system based on tonsillar hypertrophy, adenoid hypertrophy, and neck circumference has sensitivity and specificity of 62% and 100% in diagnosing OSAS.