Hypercalcaemia is common in patients with malignancy, but is rare in seminoma with only eight cases reported in the literature. We present an unusual case of a 36-year-old man who presented with hypercalcaemia and stage 3 acute kidney injury. He presented initially with headache and malaise, and was found to have markedly deranged blood tests. He underwent a renal biopsy before imaging confirmed an unexpected large abdominal mass, which was confirmed histologically to be a seminoma. He was referred to a tertiary oncology centre, and underwent emergency chemotherapy and radical resection with no evidence of recurrence to this date and with return to normocalcaemia.