Background: polisomnography is the gold standard for the diagnosis of Obstructive Sleep Apnea Syndrome (OSAS), but use has been limit because of the high cost and technical complexity. In recent years nocturnal oximetry has been recognized as a valid auxiliary method for the diagnosis of OSAS; frequently this is preceded by the application of the Pediatric Sleep Questionnaire (PSQ), a validated screening test for OSAS.Aims and objetives: our objetive was to inquire if some physical characteristics or PSQ subscales could differentiate, between children with positive PSQ (score greater or equal to 0.33), those with nocturnal oximetry abnormalities.Methods: we included baseline data from children with positive PSQ which were subsequently studied with home nocturnal oximetry. Children with craniofacial malformations or other syndromes were excluded. Children were grouped according to oximetry result (Desaturation Index >1) and clinical characteristics, PSQ subscales, and other oximetry parameters were compared between groups.Results: we include 91 children (6 ± 3 years); 46 (50%) with abnormal oximetry. We found no differences between groups in the following parameters: age and sex, total PSQ, PSQ nocturnal symptoms, PSQ diurnal symptoms, PSQ behavioral, BMI, mouth breathing, Mallampati score, degree of tonsillar hypertrophy, recurrent wheezing. In nocturnal oximetries the desaturation index, minimal saturation, and time under 90 % were significantly worse in the group with positive oximetry (p 0.004, 0.000 and 0.000 respectively).Conclusions: in children with positive PSQ, PSQ subscales and clinical characteristics were similar in children with normal or pathological oximetry.