Recombinant Tumour Necrosis Factor (rHuTNF) was locally applied to 18 patients with gynaecological tumours and recurrent malignant pleural effusions. Twenty-nine administrations with doses between 0.10 mg and 0.50 mg were carried out. Side-effects were flu-like symptoms (41%), fever/chill (34%), fatigue/malaise (28%), nausea/vomiting (10%), chest pain (14%). A dose-toxicity or dose-response relationship could not be established. Eighty-eight percent of the patients treated with rHuTNF did not suffer from any recurrent effusion within 4 weeks after treatment. Regarding the total survival time after therapy with rHuTNF 78% of all patients did not require any further pleural aspiration. Instillation of rHuTNF appears to be an effective method which can be used for pleurodesis with relatively few side-effects. It is a treatment which can also be applied to patients who are in a poor general state of health. It is especially recommendable since it can be successfully applied even after other pleurodesis devices have failed.