Cisplatin lipiodol suspension (CLS: cisplatin 20 mg/ml) was percutaneously injected (cisplatin dose, 2, 4 or 6 mg/kg) in normal lungs of 10 rabbits (1.9-2.3 kg) to assess the safety and feasibility of intratumoral injection of CLS for lung cancer. Histological study revealed acute and chronic infiltrates with bronchiolitis and immature fibrosis at the injected lung tissue even at four weeks after injection. Intrathoracic leaks of CLS produced mild and focal fibrinous pleuritis. Intrabronchial leaks of CLS produced peripheral bronchiolitis with regenerative epithelia. However, no noxious parenchymal damage in the lung and surrounding tissues was noted. Neither oil embolism in brain nor renal toxicity was demonstrated. Seven of eight rabbits showed an increase in body weight. Concentration levels of plasma platinum were lower when compared with intravenous injection of cisplatin in the rabbit: highest at 30 minutes and unmeasurable one week after injection. Lipiodol accumulation in mediastinal lymph nodes was demonstrated in two of nine rabbits by X-ray examination, suggesting intralymphatic drainage of CLS. Intratumoral injection of CLS is safe even with CLS leaks in surrounding normal lung tissues and may be a potent therapy for controlling mediastinal lymph nodes metastasized from lung cancer as well as the primary tumor.