A combined E. coli and C. perfringens Type B, C and D vaccine for pigs. For the passive protection of piglets by the active immunisation of breeding sows and gilts to prevent neonatal colibacillosis caused by K99 bearing strains of E. coli; to reduce neonatal colibacillosis caused by K88ab, K88ac and 987P bearing strains of E. coli and C. perfringens Type C necrotising infectious enteritis.