In 30 patients with suspected or, respectively 27 patients with confirmed, sleep apnea syndrome, 24-h esophagus pH metering was carried out. The patients were divided into two groups (number of apnea per 6 h > or < 100). A pH value of < 4 was defined as a pathological reflux when it occurred in total in at least 4% of the measuring period. Pathological reflux was encountered in 76% of the light SAS group and in 68% of the patients with severe SAS. Positional variations through upright and supine positions were apparent but not significant. Further investigations are therefore necessary to evaluate the relationships between degree of severity, position, and accompanying diseases.