Twenty-two consecutive patients with malignant pleural effusions (MPE) were treated with intrapleural Corynebacterium parvum 7.30; 2 of these died a few days after the treatment, and 10 had favorable responses. The other 9 patients had a PF pH < 7.30: all had favorable responses. The leukocytes, the lymphocyte subsets, the monocytes, the NK lymphocytes, and their PF/B ratios did not differ significantly before and after CBP treatment. Our study confirms that intrapleural CBP is an effective and simple method to control MPE. The combination of MP with CBP did not prevent effective pleurodesis and seems to reduce the frequency of adverse reactions, except fever.