Primary hyperparathyroidism is seldom associated with other autoimmune disorders. The presence of normocalcemia in primary hyperparathyroidism should prompt the physician to look for vitamin D deficiency. This observation concerns a 34-year-old vegetarian woman with combined primary hyperparathyroidism, Graves' disease, and celiac disease. The patient presented with severe bone deformities; she was unable to walk, and had severe muscular weakness and weight loss. Biochemical findings revealed severe hyperparathyroidism with normocalcemia, hypophosphatemia, very low urinary calcium, and low 25-hydroxy vitamin D level. Thyroid tests showed hyperthyroidism with positive thyroid receptor antibodies, confirming the presence of Graves' disease. Positive antigliadin and antireticulin antibodies and complete villous atrophy on duodenal biopsy established the presence of celiac disease. The patient underwent a near-total thyroidectomy, with the removal of a parathyroid adenoma. To our knowledge, this observation is the first finding of an association between celiac disease, Graves' disease, and primary hyperparathyroidism. It emphasizes the need to rule out intestinal malabsorption in the case of normocalcemic hyperparathyroidism.