Extensive reports on losses in zoo animals are very rare. As fas as we know only London, Paris, Philadelphia and Washington give yearly reports. Of these London and Paris give very complete information. One of the reasons that so few zoos publish their results may be that it is always more pleasant to give information about successes than about failures. In our opinion, however, it is no use to disguise the truth and for other zoos it can be very useful to have the opportunity to compare results. The period described in this paper is part of an important era in the history of our zoo, a period of reconstruction, rebuilding and, of increasing the collection. This period will last another 10-15 years or so as at that time the really old and worn-out buildings will have been replaced and appropriate facilities for the veterinarian will have been achieved. At the same time this period has seen great advances in veterinary care. The Cap-Chur pistol in use in our zoo since 1960 made injection possible of any animal at any time. The increasing arsenal of therapeutics and the international contacts by way of the international symposia on diseases of zoo animals have contributed largely to a better medical care of zoo animals. Thus prevention of diseases is becoming more and more important. In our opinion the effective disinfectant halamid (Chloraminum) plays an important rôle in this respect.