Serum gastrin and lower esophageal sphincter (LES) responses to somatostatin infusion were evaluated in ten normal subjects and in nine achalasic patients in order to determine evidence of hormonal (presumably gastrin)control of LES pressure. After somatostatin infusion, a significant decrease of serum gastrin was observed in normal subjects at 30 min (81.6 +/- 3.2 versus 40.0 +/- 4.7 pg/ml; p less than 0.01) and a rapid increase of LES pressure was also observed (26.0 +/- 1.3 versus 34.1 +/- 1.6 mmHg; p less than 0.01). In achalasia no change was observed in serum gastrin concentration after somatostatin infusion. LES pressure at 20 min however significantly decreased (45.8 +/- 7.6 versus 31.6 +/- 2.3 mmHg; p less than 0.05). Endogenous gastrin is not a major control factor for LES pressure in either normal or achalasic subjects.