In 11 patients with chronic snoring and 12 subjects with obstructive apnoea syndrome the percentage of snoring duration above a preset sound pressure level during one night's sleep was correlated with the radiocephalometric data. Cephalometric distances PAS, PM-Pg, MP-H and angles SNA and SNB representing measures for posterior airway space, size of soft palate, relative position of hyoid bone and relative position of maxilla and mandibula were evaluated. Each patient showed pathological deviations from normal values in at least one of the cephalometric parameters. A significant correlation between snoring duration and a single cephalometric distance could not be found. However, an index combining pathological deviations from all three cephalometric distances showed a highly significant correlation with snoring duration (p less than 0.01 - Fig. 11), as did deviations from normal values of angle SNB (p less than 0.03 - Fig. 10). Our findings indicate that snoring and obstructive apnoea syndrome are not only caused by neurologic dysregulation, and that in addition specific craniofacial anomalies are prerequisites for the development of the disease. For the first time it is demonstrated that these anomalies exist in chronic snorers as well as in apnoeic patients. Our findings support Lugaresi's hypothesis that heavy snoring and obstructive apnoea syndrome are based on the same defect and differ in severity only.