Gastrin is a peptide hormone important in acid regulation, growth of enterochromaffin cells of the oxyntic mucosa, and smooth muscle contractility. We isolated a genomic clone of gastrin from a SV-129 murine genomic library. The murine gastrin gene contains an open reading frame of 101 amino acids. The deduced amino acid sequence has 91.1% homology with the rat and 67.3% homology with the human analogue. Southern blot analysis of the murine gastrin clone gave the same restriction pattern as that seen from mouse kidney genomic DNA, consistent with this being a single copy of the gastrin gene in the mouse genome. Transfection studies demonstrated that the murine gastrin gene expression is stimulated by epidermal growth factor to the same extent as the human gastrin gene.