Islet amyloid polypeptide (IAPP) or amylin is a pancreatic islet hormone which was first found in amyloid in insulinomas and in pancreases of patients with type 2 diabetes. In rat a similar polypeptide occurs; however, pancreatic amyloid in this species has not been described. Here we report the structure of the rat and human IAPP gene. Both consist of three exons and two introns which are very similar. The upstream sequence of the rat IAPP gene contains a TATA-box, a CCAAT-sequence and a GT-element, whereas the upstream sequence of the human IAPP gene contains a TATA-box and a rat insulin enhancer-like sequence. This suggests that the rat and human IAPP gene may be controlled differently at the transcriptional level.