Comorbidities are a risk factor for patients with COVID-19 and the mechanisms of disease remain unclear. The aim of this paper is to present a case report of an COVID-19 patient with severe hypocalcaemia. This is a report of an 81-year-old female, suffered from myalgia and fatigue for more than 3–4 weeks. Fever and cough appear 2 days before she presented to the emergency room. On physical examination, she was febrile with a temperature of 38.8°C, accompanied by cough, sore throat, headache, fatigue, and muscle ache. Her past medical history was remarkable with no chronic disease. She had lymphopenia. Laboratory test revealed moderate liver dysfunction, hypoalbuminemia, and severe hypocalcaemia (serum corrected calcium level: 5.7 mg/dL). Parathyroid hormone (PTH) was 107.9 pg/mL (range: 15–65) and 25(OH)2D levels was 4.5 ng/mL (range: 25–80). Chest CT scan detected peripheral ground-glass opacity. Throat swab for coronavirus by RT-PCRassay tested positive for the virus. She was treated with lopinavir/ritonavir, third generation cephalosporin, anticoagulant, daily high-dose calcium acetate, vitamin D3, fresh frozen plasma and oxygen therapy. She was discharged after two negative throat swab tests for coronavirus by conventional RT-PCR.