There have been many reports of altered pancreas size in diseases of the endocrine and exocrine pancreas, but few attempts to quantify such changes. The aim of this study was to conduct a systematic literature review, documenting the methodology, and quantitative data in studies reporting on pancreas size. Three electronic databases (Embase, Scopus, and MEDLINE) were searched by two reviewers independently. Studies of humans were included if they compared pancreas size (reported as pancreas diameters, areas, and/or lengths) between diseased populations and controls. A total of 28 studies with 3,810 individuals were included. Among these, 22 measured pancreas diameters, seven measured pancreas areas, and one measured pancreas lengths. The most common landmark for the head of the pancreas was the confluence of the superior mesenteric and splenic veins (three out of nine studies, 33.3%); for the body it was the superior mesenteric artery (seven out of nine, 77.8%); for the tail it was the internal border of the left kidney (two out of six, 33.3%). Pancreas diameters and areas tended to be smaller in diabetes mellitus, the extent of reduction being greater in individuals with type 1 than type 2 diabetes. Pancreas diameters tended to be greater in acute pancreatitis and pancreatic cancer but not in chronic pancreatitis. Pancreas diameters are a clinically relevant measure for diseases of the endocrine and exocrine pancreas. Consensus guidelines need to be developed to standardize their measurements. Clin. Anat. 31:913–926, 2018. © 2018 Wiley Periodicals, Inc.