Fifty‐four consecutive patients with malignant effusions either pleural or peritoneal were treated by a simple aspiration followed by the administration of bleomycin to prevent a recurrence. All patients were followed up until reaccumulation of the effusion or death, with assessments being made of the patient's response at 30 days, 60 days, 90 days, 6 months, 1 year and then annually. There were 42 evaluable patients at 30 days, when the overall response rate for pleural effusions was 80.5% (21/26) and 62.5% (10/16) for peritoneal effusions. Patients who developed an effusion from primary breast neoplasms responded better than other groups, with an overall rate of 81% and 80% for pleural and peritoneal effusions respectively. Thirty percent (13) of the patients whose effusions was controlled by bleomycin required a further aspiration due to a recurrent effusions 9% (4) within the first 90 days and the remainder 21% (9) between 3 and 45 months after initial treatment. Altogether 19% (8/42) of the evaluable patients were effusion free at 1 year and 12% (5/42) clear at 3 years, but only two patients were still alive at four years. Side effects were minimal as 92% (50/54) patients treated experienced no adverse effects and there was no evidence of myelosuppression. The dose of bleomycin instilled varied between 60 mg and 180 mg, with 60 mg being given to 58% of patients and 90 mg to 30%, but there was no evidence to suggest that doses higher than 60 mg were more effective. The author concludes that the instillation of bleomycin following the simple aspiration of a malignant effusion is a safe, effective treatment which can benefit patients with this distressing complication of their malignant disease.