It is well known that a number of chemotherapeutic agents are able to induce procoagulating activity not only in neoplastic cells but also in normal, monocyte/macrophage cells, and some of them, including cisplatin, even increase procoagulating activity of the factor already expressed, providing a further example of the possible co-participation of chemotherapy in the onset of thrombotic complications in cancer patients. Carboplatin is an analogue of cisplatin but differs strikingly in terms of its collateral effects, in particular being less oto- and nephrotoxic. To the authors' knowledge there are no data regarding the possible effect of carboplatin on lympho/monocyte procoagulating activity. This study shows that not only platin but also carboplatin is able to increment the levels of lympho/monocyte procoagulating activity in vitro, with a dose-dependent effect, and to synergize with bacterial endotoxin in increasing this leukocyte activity, although the synergic effect is significantly greater in the case of carboplatin. The importance of these findings at a practical and clinical and clinical level still remains to be defined, in particular in the light of the different pharmacokinetic behaviour of these two chemotherapeutic agents and in the context of those neoplastic diseases for which cisplatin and carboplatin treatment is most frequently used.