While arginine deiminase (ADI) from Mycoplasma arginini is a well-known anticancer agent, very little is known about any such role of ADI from other bacteria. Additionally, M. arginini ADI is believed to exert its anticancer activity due to depletion of arginine from cancer cells. In this report, we demonstrate anticancer activity of ADI from Pseudomonas aeruginosa. We have also cloned and expressed a truncated form from the P. aeruginosa ADI which harbors a caspase recruitment domain (CARD). This polypeptide, called Pa-CARD, demonstrates anticancer activity without exhibiting any ADI enzymatic activity by inducing apoptosis in cancer cells but not in normal cells. Microarray experiments suggest that Pa-CARD modulates NF-kB signaling pathway genes to exert its anticancer activity.