Patients with prostatic cancer frequently require evaluation of bony metastases as well as renal function. 99mTc-methylene diphosphonate, a commonly used bone-imaging agent, is about 60 per cent localized in the bony skeleton and about 40 per cent excreted by the kidneys. Immediate imaging after intravenous injection of the isotope may yield high-quality radionuclide nephrourograms, which provide excellent visual and graphic displays of renal anatomy and excretory function. Our preliminary studies suggest that the immediate 99mTc-methylene diphosphonate scan may usefully expand the value of a routine bone scan to screen for ureteral obstruction. Patients with underlying malignancy who require simultaneous evaluation and follow-up of bony metastases and renal function might be conveniently served by the dual functions of the expanded bone scan to include immediate imaging of the kidneys.