To our knowledge, this is the first reported case of clinical onset of celiac disease (CD) following duodenal switch surgery. A 61-year-old obese woman developed severe diarrhea soon after bariatric surgery (BS), which was unresponsive to standard medical treatment. After the most common diarrhea etiologies in the immediate postoperative period have been excluded, serological tests were performed. Final diagnosis was determined by anti-tissue transglutaminase antibody positivity. In light of this case report, we propose that CD should be ruled out in any patient presenting with typical or atypical symptoms after BS, regardless of the latency of onset.