Context.-Reviewers increasingly are asked to review manuscripts from outside their own country, but whether they are more likely to recommend acceptance of such manuscripts is not known. Objective.-To assess whether US reviewers or non-US reviewers evaluate manuscripts differently, depending on whether the manuscripts are submitted from outside the United States or from the United States. Design and Setting.-A retrospective analysis of all original submissions received by Gastroenterology in 1995 and 1996. Reviewers ranked manuscripts in 4 decision categories: accept, provisionally accept, reject with resubmission, or reject. Main Outcome Measure.-Ranking of papers based on nationality of authors and reviewers. Results.-The percentage of non-US manuscripts placed in each decision category by US (n=2355) and non-US reviewers (n=1297) was nearly identical (P=.31). However, US reviewers recommended acceptance of papers submitted by US authors more often than did non-US reviewers (P=.001). Non-US reviewers ranked US papers slightly more favorably than non-US papers (P=.09), while US reviewers ranked US papers much more favorably (P=.001). Conclusions.-Reviewers from the United States and outside the United States evaluate non-US papers similarly and evaluate papers submitted by US authors more favorably, with US reviewers having a significant preference for US papers.