Decreased lower esophageal sphincter (LES) pressure after ingestion of chocolate has been previously noted. We have further evaluated the effect of chocolate on the known ability of gastric alkalinization or bethanechol to increase LES tone. 9 normal subjects were studied using an infused open-tip recording system. Pressure was monitored for a 15-min basal period, and for 60 min after ingestion of 120 ml of chocolate syrup either alone or with the concurrent administration of commercial antacid, oral bethanechol, or subcutaneous bethanechol. After chocolate ingestion, mean basal LES pressure of 14.6 +/- 1.1 (+/-SEM) mm Hg decreased significantly (P less than 0.01) to 7.9 +/- 1.3 mm Hg. An identical LES response occurred when antacid was given with the chocolate dose. Oral bethanechol (25 mg) and chocolate together resulted in lesser decreases in LES pressure. Subcutaneous bethanechol (5 mg) and chocolate produced significant increases (P less than 0.05) in sphincter pressure, although of lesser magnitude than reported with bethanechol alone. These results indicate that the adverse effect of chocolate on the LES is not reversed by gastric alkalinization and suggest that bethanechol in sufficient dose may overcome chocolate-induced decreases in LES pressure.