The Clostridium septicum alpha toxin and the Clostridium perfringens beta toxin are examples of pore-forming toxins that exhibit several different features. The cell types that are targeted by these toxins reflect the effect these toxins have on the host during infection with either organism. Alpha toxin elicits a rapid shock-like syndrome, whereas beta toxin appears to induce a variety of neurological effects. The effects of the purified toxins appear to mimic some of the features of the animal and human diseases caused by C. septicum and C. perfringens. This review, examines the current state of knowledge for the cytolytic mechanism, role in pathogenesis and structure of these two toxins. (C) 2001 Elsevier Science B.V. All rights reserved.