Nonclassical celiac disease is a diagnostic challenge for the practitioner. We report a case of a 28-year-old Moroccan woman who had been experiencing polyarthralgia and joint swelling for 8 weeks, despite treatment with nonsteroidal anti-inflammatory drugs and corticosteroids. On physical examination, there was effusion in the proximal interphalangeal joints, metacarpophalangeal joints, wrists, knees, and ankles. Laboratory tests revealed microcytic anemia, elevated levels of inflammation markers, low ferritin, and a low vitamin D level. An upper gastrointestinal endoscopy was performed to investigate the cause of anemia, revealing the loss of duodenal folds. Subsequently, a duodenal biopsy was performed, and serological testing for celiac disease was requested. Anti-transglutaminase-2 antibodies were elevated at 200 U/ml (normal < 15U/ml). The duodenal biopsy showed flattened duodenal mucosal epithelium. The patient was diagnosed with celiac disease. A gluten-free diet was started. Her joint symptoms resolved in 3 weeks. All blood tests returned to normal levels after 48 weeks. This case illustrates that celiac disease should be considered in cases of arthritis with an initial negative etiological workup.