OBJECTIVE: To validate the BREAS SC20 (Breas Medical AB, Mölnlyke, Sweden) polygraphic screening device, comparing it with conventional polysomnography (PSG), in the diagnosis of sleep apnea-hypopnea syndrome. A validity study of the diagnostic test was carried out at the sleep clinic of a tertiary hospital. PATIENTS AND METHODS: Seventy patients clinically suspected of sleep apnea-hypopnea syndrome and treated at the sleep laboratory of the Hospital Txagorritxu, Vitoria, Spain, from November, 2001 until August, 2002 were consecutively enrolled in the study. Patient characteristics, comorbidities, and results on the Epworth sleepiness scale were recorded. The apneahypopnea index (AHI) per hour of sleep was determined by PSG; the respiratory events index (REI) per hour of screening was determined by the polygraphic screening device. RESULTS: Sixty studies were valid (77% were men; mean [SD] age: 51.6 [13.2]; body mass index: 30.3 [5]; AHI: 31.0 [27.6]). The intraclass correlation coefficient between the AHI by PSG and the manual REI was 0.92. The mean difference between the AHI and the manual REI was 2.92 (9.75). The area under the receiver operating characteristic curve was 0.924 for the cut point AHI ≥5. The optimal cut point for an AHI ≥5 was 3.6 in the REI (98% sensitivity). The respiratory screening device correctly classified 90% to 95% of the patients. CONCLUSIONS: The BREAS SC20 is a valid system for identifying patients clinically suspected of sleep apnea-hypopnea syndrome.