Abstract: The present invention provides novel peptides and vaccines containing them capable of inducing production of antibodies directed against Clostridium perfringens alpha-toxin (CPa) in animals to which they are administered and thereby providing prophylaxis against infection by Clostridium perfringens and/or the alpha-toxin itself. Particularly the present invention provides such a vaccine that is relatively safe and simple to produce. e.g. by genetic engineering means. Preferred peptides comprise theo amino acid sequence of Clostridium perfringens alpha-toxin from amino acid 247 to 370 but lack the epitopes necessary for phospholipase C and/or sphingomyelin hydrolysing activity found between amino acids 1 to 240 of that sequence. Further provided are antisera and antibodies raised to the peptides and vaccines of the present invention, and particularly monoclonal antibodies and hybridoma cell lines for their production.