We recently showed that enteral glucose-induced release of glucagon and glucose-dependent insulinotropic polypeptide (GIP) is increased in morbidly obese humans, while glucagon-like peptide-1 (GLP-1) release is decreased - changes that promote hyperinsulinemia and hyperglycemia. Jejunal expression of prohormone convertase-1 (PCSK1, the proteolytic enzyme for GIP and GLP-1 production) is also decreased in morbidly obese patients with type 2 diabetes compared to those without diabetes which may contribute to hyperglycemia. However, regional expression of PCSK1, and of PCSK2 (the proteolytic enzyme for glucagon production) has not been evaluated in relation to obesity. Endoscopic biopsies were collected from the duodenum of lean and obese subjects while left colon biopsies were collected from separate lean and obese subjects, none of whom had diabetes. PCSK1 and PCSK2 transcript levels were assessed by qPCR. PCSK1 transcripts were 5-fold higher (P<0.001) in duodenum than left colon of lean subjects, while PCSK2 transcripts - present at half the level of PCSK1 in the duodenum (P < 0.001) - were 8-fold higher in duodenum than left colon (P<0.001). There were no differences in PCSK1 or PCSK2 transcript distribution or abundance between lean and morbidly obese subjects. In conclusion: (i) duodenal L-cells may have greater capacity for incretin hormone biosynthesis and release, despite greater L-cell density in colon; (ii) the relatively high level of duodenal PCSK2 expression supports the concept of gut-derived glucagon production in humans; and (iii) transcriptional differences in PCSK1 or 2 do not underlie reduced GLP-1 production or augmented glucagon release in human obesity.