A method is described for determining total platinum in tissues of animals receiving cisplatin. The method is based on total combustion of the tissue, leaving a platinum residue devoid of organic material that can be dissolved inaqua regiaand analyzed by carbon-rod furnace atomic absorption spectrophotometry. Combustion eliminates matrix effects in final read-out, providing a means for precisely and reproducibly analyzing a variety of tissues. Platinum levels of 200 ng/0.5 g of sample can readily be analyzed with recoveries from all tissues approaching 100%. The validity of the method is demonstrated by giving rats intravenous doses of cisplatin and subsequently measuring tissue levels of platinum.