Aim: To investigate the cytokine-stimulating activity of several Mycobacterium phlei cell wall extracts. The bacillus Calmette-Guerin application is the gold standard treatment for some types of superficial bladder carcinoma. However, its usage is limited due to its harmful side effects. Intensive research has been carried out to find less toxic and more potent therapeutic agents for treatment. Researchers focus on M. phlei for this purpose. The cell wall extract of M. phlei is sufficient for antitumoral activity.