Renal metastasis of localized tumours in the economy are rare. In our series of 162 renal tumours only 3 were metastatic. Even more unusual is that the metastasis should be the presenting form. Such is the case we are reporting: a 59 year-old male complaining from back pain and toxic syndrome. Supplementary examinations were performed sequentially until arriving at an open biopsy which confirmed the oat cell histology. The paper explains the results from the various examinations. The ominous prognosis of this histology is illustrated.