The intratumoral distribution of cisplatin was studied in terms of platinum concentrations In tissue pleces and Immunohistochemically detected cisplatin-DNA adducts in xenografted tumors on nude mice. Heterogeneities in drug distribution were calculated as standard deviations and coefficients of variation. A three-dimensional image of adduct distribution was produced which showed regions with low adduct levels to be topographically connected also in three dimensions. A model was presented for investigating the potential Influence of vascularization and cell proliferation on intratumoral adduct distribution by using different immunohistochemical stainings of parallel tissue sections. A weak but significant correlation was found between claplatin-DNA adducts and proliferation, which might indicate that the drug uptake and adduct formation is Increased in proliferating cells.