In most cases of parathyroid adenoma (PA), it is not palpable and physical examination shows no remarkable findings. Hence diagnosis requires an index of suspicion. The current paper describes four cases of severe hypercalcemia secondary to PA. Case 1 - 29 years old Sudanese female with history of nausea/vomiting, fatigue, loss of appetite and bone aches. She had large palpable left lower neck swelling, and high calcium and PTH. Ultrasound (US) neck and SPECT/CT scan after sestamibi injection showed left inferior PA. Case 2-73 years old Sudanese male referred with history of abdominal pain and flatulence. He had severely high calcium, elevated parathormone (PTH), and high 24-hour urine calcium. US and SPECT/CT showed a left inferior PA. Case 3-54 years old Bangladeshi male, referred with history of renal colic/urolithiasis. Laboratory results showed severely high calcium and PTH levels. US and SPECT/CT scan showed right inferior PA. Case 4-35 years old Tunisian female, 12 weeks pregnant, referred with recurrent nausea and vomiting of increasing frequency from the second week of pregnancy. Laboratory tests revealed severe hypercalcemia and high PTH. US showed two parathyroid lesions. The patients were admitted as emergency cases and investigations diagnosed severe hypercalcemia secondary to PA. All patients underwent neck exploration and PA excision. Histology confirmed PA. The four cases were swiftly assessed and treated before progressing into the more serious hypercalcemic crisis which can lead to grave consequences, particularly in the case of the pregnant female. All patients recovered with no complications and were clinically well with normal calcium level on follow up. Severe hypercalcemia must be swiftly and thoroughly assessed to prevent the more serious hypercalcemic crisis. Clinicians need to be suspicious of parathyroid adenoma as a probable cause. Severe hypercalcemia is often accompanied with vomiting, and in pregnant females, this could be mistaken for hyperemesis gravidarum. Excision of the parathyroid adenoma treats the condition and follow up of serum calcium and PTH confirms the favorable outcome of surgery.