FDG-PET is useful for both topographic and metabolic analysis of metastatic cells. It uses a radioactive metabolite integrated into a molecule which penetrates into the tumoral cells. At present, concerning urologic carcinoma, there is no indication for its use in routine to diagnose primary tumors or to explore their development. However it can be useful for minor recurrences for which CT scan and MRI cannot be conclusive. In particular for kidney and urothelial carcinoma it may represent a diagnostic benefit. Nevertheless, interpretation is often made difficult by tracer urinary excretion. New radio tracers are being tested and will probably lead to new indications. Research on androgen receptors and molecular imaging is ongoing.