Mortality from scours caused by E. coli was observed among piglets on a pig breeding and multiplying farm in 't Zand over a considerable period. As the usual method of treatment failed to produce the desired results, E. coli vaccine was administered to a number of farrowing sows. Alle piglets born to vaccinated sows were reared without any problems, whereas a number of piglets of non-vaccinated sows died from scours caused by E. coli. Moreover, the growth of piglets of vaccinated sows was superior to that of piglets of non-vaccinated sows. An optimum vaccination programme is described.