Pulmonary damage induced by cytostatics is a rare, although clinically important complication in the chemotherapy of tumours. Early recognition of this partly toxically and partly hypersensitively conditioned processes is of great prognostic importance, since in many cases the unchecked progress of the damage, eventually resulting in pulmonary fibrosis with respiratory insufficiency, can be prevent only by discontinuing the treatment well in time. Examinations of the pulmonary function enable a very early detection of functional disturbances in a lung which has been damaged by cytostatics. Since even the later roentgenological findings are non-specific, final confirmation of the diagnosis is possible by pulmonary biopsy only. Lungs damaged by cytostatics show histologically characteristic patterns, which, however, are non-specific and can become manifest in the same manner, inter alia, in shock and in intoxication by paraquat, since the basic principle of damage underlying these processes is very similar.