Bladder carcinoma is among the most frequent cancer types especially among men. Intravesical instillation of attenuated strain of Mycobacterium bovis, Bacillus Calmette-Guerin is the standard treatment of medium and high risk patients. It is thought that the effect is through stimulation of the immune system. Since, the use of live mycobacteria may yield to deathly side effects, intensive research is in progress to obtain more potent and less harmful treatment alternatives. Applications of mycobacteria together with other immunostimulants, use of genetically modified organisms, or use of nonpathogenic strains such as Mycobacterium phlei are examples to such researches. Cell wall is sufficient for antitumoral activity. Our research group investigated the immunostimulating activity of several cell wall subfractions of Mycobacterium phlei and showed that the heat stable, water soluble structures, instable to protein denaturating agents and do not contain DNA might be responsible for these effects. Next, immunostimulating activity of 88 mycobacteria strains were investigated and found out that 12 nonpathogenic, rapid growing strains might be an alternative to Mycobacterium phlei. Separation of the cell wall components of these strains by multidimensional HPLC and identification of the structures is in progress. The findings so far obtained resemble the findings obtained with Mycobacterium phlei. More detailed peptidomics and proteomics studies to isolate and characterize these structures may shed light on the mechanism of action of these components and lead to preparation of less harmful antitumoral agents. Further study with animal models is also required to show the in vivo effects of these substances.