Introduction: There is a huge variety of hypocalcaemia aetiologies. Out of all these reasons hypoparathyroidism is one of the rarest. The most common cause of this malfunction is accidental excision of parathyroid gland during thyroid gland surgery. Inflammation or metabolic disorders are very rare. When we diagnose hypoparathyroidism, polyendocrine syndromes must be always taken into account and we are obliged to check whether other endocrine glands work properly. Hypocalcaemia can be asymptomatic. However some most common signs of this disorder are: laryngospasm, muscle cramps (especially during physical effort), tetany, nutritional problems among infants, convulsions, paraesthesia, Trousseau and Chvostek symptoms, longer QT>450 ms. Aim of the study: We present the case of 8 year old child suffering from idiopathic hypoparathyroidism, epilepsy and immune deficiency. This case is quite interesting as the most spectacular hypocalcaemia symptom which tetany is, was initially taken for epilepsy. Epilepsy was diagnosed after the boy choked because of the braces which misplaced during the night. As a result his central nervous system suffered from short-lived oxygen deficiency. Maybe these two diseases (hypoparathyroidism and epilepsy) coexist or epilepsy was just a mask of severe hypocalcaemia? Conclusions: Diagnosing epilepsy we cannot omit tests concerning calcium and phosphate blood levels.