Glucagon-like peptide-1^7–36NH2 (GLP-1^7–36NH2) is a potent stimulator of insulin secretion, as well as of somatostatin-14 (SS-14) release from the pancreatic and gastric D-cells. To investigate the possible effects of this peptide on release of intestinal somatostatin (SS-28 and SS-14), rat intestinal cultures were treated with 10⁻¹²–10⁻⁶ M GLP-1^7–36NH2, as well as with the structurally related peptides, GLP-1^1–36NH2 and GLP-2. Both forms of GLP-1 stimulated dose-dependent increases in intestinal somatostatin; secretion reached 643±126% of controls (p<0.001) after treatment with 10⁻⁶ M GLP-1^7–36NH2, and 398±76% of controls (p<0.001) after 10⁻⁶ M GLP-1^1–36NH2. Thus, GLP-1^7–36NH2 was more effective than GLP-1^1–36NH2 in stimulating secretion of intestinal somatostatin-like immunoreactivity (SLI) (p<0.05). GLP-2 did not affect intestinal somatostatin release. Gel permeation analysis demonstrated that 10⁻⁶ M GLP-1^7–36NH2 stimulated SS-28 by 2.9±0.4-fold and SS-14 by 9.1±3.7-fold, whereas GLP-1^1–36NH2 exerted equivalent effects (2.8±0.9-fold) on both forms of somatostatin. These findings define a novel biological role for GLP-1^7–36NH2 in the regulation of intestinal somatostatin secretion, and demonstrate that GLP-1^1–36NH2 exerts unique biological activities in this system.