The aim of this study was to visualize non-invasively the uptake of platinum in tumours and tissues after treatment with cisplatin. 191Pt-cisplatin was synthesized from 191PtCl4 with rigorous pharmaceutical quality control. The uptake of platinum by both tumorous and healthy tissues was studied by gamma camera imaging in 14 patients, 5 of whom showed a clear uptake of platinum in regions corresponding to known tumour sites. Maximum concentrations of platinum in the tumours were on average 4.9+/-1.0 microg/g, when normalized to an administered amount of 180 mg cisplatin. In all the patients, the liver was the organ that showed the highest uptake. Platinum uptake was also seen in the spleen, gall bladder, gastrointestinal tract, bladder, kidneys, ureter, neck and mediastinum and urogenital region. By using in-house production of 191Pt-cisplatin, it was possible to monitor the uptake of platinum in tumorous tissues and healthy organs.