Celiac disease (CD) affects up to 1% of the general population. Classically, it manifests with intestinal symptoms (diarrhea, steatorrhea, abdominal pain or discomfort) associated with weight loss and anemia. Seizure is a rare form of presentation of CD. A 13-year-old female patient with Down syndrome was admitted to the pediatric emergency department with generalized tonicclonic seizure in addition to numbness around the mouth, paresthesias, and muscular cramping for seven days. Investigations revealed severe hypocalcemia and vitamin D deficiency, which were a consequence of malabsorption secondary to histopathologically confirmed CD. Physicians should be aware that unrecognized CD can cause severe hypocalcemia.