Fifteen consecutive patients referred because of suspicion that gastroesophageal reflux was the cause of their chronic, unexplained cough underwent combined ambulatory esophageal manometry and pH-metry in order to correlate cough episodes with gastroesophageal and gastrohypopharyngeal acid reflux. Cough episodes, which were recognized manometrically as phasic bursts of brief simultaneous elevations in all intraesophageal pressure leads, were markedly underreported by patients. If all cough events were considered, that is, single coughs plus "bursts" of coughing, patients reported on average 10% of the total manometrically recorded coughs, whereas if only cough bursts were considered, patients reported an average of 23%. Gastrohypopharyngeal acid reflux preceded 1% and 1.8%, whereas gastroesophageal reflux preceded 9% and 13%, of the total coughs and cough bursts, respectively. One percent and 1.6% of total coughs and cough bursts, respectively, appeared to precipitate reflux. Gastrohypopharyngeal reflux events were rare, with only 15 episodes recorded in nine of the 15 patients. In 13 asymptomatic volunteers, no episodes of gastrohypopharyngeal acid reflux were recorded. This study suggests that ambulatory esophageal manometry/pH-metry provides an objective measure of temporal relationships between cough episodes and acid reflux events that is superior to relying on the patients' reporting of cough episodes. In this study population, the incidence of a direct temporal correlation between reflux and cough episodes was relatively low. However, a high proportion of patients had gastrohypopharyngeal reflux, suggesting that acid reflux to the laryngeal inlet may indirectly play a role in chronic unexplained cough.