The objective of this study was to determine the accuracy and practicality of home testing for pediatric obstructive sleep apnea syndrome (OSAS) secondary to adenotonsillar hypertrophy. Twenty-one children aged 2-12 years and referred for possible OSAS were studied twice, once at home and once in the sleep laboratory. The home test consisted of two parts: 1) a cardiorespiratory recording of saturation (SaO2), pulse rate, pulse waveform, electrocardiogram, and respiratory inductive plethysmography; and 2) an 8-hour videotape recording of the sleeping child. In the laboratory, standard nocturnal polysomnography including electroencephalography was performed. Experiences with another 62 children who underwent home testing alone were also reviewed and are reported. At home, saturation, respiratory, and video data were obtained 96.4 +/- 13.3% (mean +/- SD) 99.4 +/- 1.6%, and 90.0 +/- 78% of the time, respectively. The sleep efficiency was greater at home than in the laboratory, 91.1 +/- 3.9% vs. 86.1 +/- 7.2%, with a mean difference of 5.0% (P < 0.01). The median environmentally induced movement/arousal index was lower in the home than in the laboratory, 0.0 (inter-quartile range, 0.0-0.3 vs. 2.4/hr (inter-quartile range 1.2-4.2), with a median difference of 2.4/h (P < 0.001). Study duration, apnea/hypopnea index, desaturation index, respiratory and spontaneous movement/arousal indices, and oxygen saturation during sleep were similar for home and laboratory studies. Although neither sleep state nor PCO2 (transcutaneous or end-tidal) was measured in the home, this information would have modified patient management in, at most, one case. In the second group of 62 children, exclusively studied at home, all studies were successfully recorded despite a wide range of sleep efficiencies, apnea/hypopnea indices, and desaturation indices. We conclude that home testing, using a simplified cardiorespiratory montage plus video recording, is accurate and of practical use in the routine evaluation of OSAS in patients with adenotonsillar hypertrophy.