Background: While employers are increasingly considering and implementing COVID-19 vaccination requirements, little is known about the reasons offered by employees seeking religious exemptions.Methods: We conducted a mixed methods analysis of all the requests for religious exemptions submitted during the initial implementation of a COVID-19 vaccination requirement at a single academic medical center in the United States.Results: Five hundred sixty-five (3.4%) employees requested religious exemptions. At least 305 (54.0%) requesters had job titles suggesting that they had direct patient contact. Four hundred (...) ninety-nine (88.3%) of requesters self-identified as Christian, of whom 120 (21.2%) identified as Roman Catholic. Requesters offered 0 to 8 (mean 2.7) categories of reasons for their request. The most frequently stated reasons pertained to the use of fetal cell lines in vaccine development and manufacturing (382, 67.6%), interest in maintaining purity (221, 39.1%), or belief in divine healing (172, 30.4%). Some requesters also volunteered evidence of the sincerity of their beliefs including examples of their religious practices (116, 20.5%), other practices (66, 11.7%), and emotional states (32, 5.7%). One hundred fifty-two applications (26.9%) contained text copied without attribution, primarily from sample religious exemption request letters available on the Internet.Conclusions: Most requesters focused on the use of fetal cell lines in the development or manufacturing of the vaccines as the justification for their request. The development of vaccines that are not reliant on fetal cell lines may increase vaccination rates. Understanding reasons for religious exemption requests may inform vaccine education and vaccination policies. (shrink)