Impaired consciousness and convulsion may be resulted from metabolic (85%) and central nervous system disorders caused by trauma, infections and fluid-electrolyte imbalance, besides epilepsy. In this study we aimed to present a case of hypocalcemia which is a rare cause of convulsion. An 80-year-old male admitted to emergency room with sudden onset of impaired consciousness and convulsions. Medical history revealed that the patient had dysarthria and ataxia due to previous cerebellar ischemic attack and also had hypertension and chronic renal failure. Clinical examination revealed a confused patient who has a moderate clinical condition and Glasgow Coma Scale score of 12, blood pressure was 130/80 mmHg, respiratory rate was 40 breaths per minute, heart rate was 80 beats per minute and sinus tachycardia rhythm was observed in the electrocardiography (ECG) examination in admission.