Currently, kidney cancer is in most cases fortuitously diagnosed by ultrasound or abdominal computed tomography, performed for non-specific clinical signs. The late-developing clinical signs are suggestive of an advanced tumour stage. Abdominal computed tomography is the key examination; it enables to establish the diagnosis and assess tumour extension. Performing a tumour biopsy is useful in patients with small tumours, when diagnostic certainty is required or when metastases or a lymphoma are suspected.