An Approach to a Long-Established Institution and the Way it is Affected by a Changing Relationship of Humans and Non-Human Animals. In this thesis I will discuss whether zoological gardens still suit today's zeitgeist. This question is approached by reconsidering the human animal relationship. The utilitarian theory is applied to this relationship as well as to the concept of a zoo. The history and idea behind the zoo are illustrated as are the different ways mankind faces animals. After a brief account of what happens at the zoo from a sociological point of view the concept of the modern zoo is characterised. Given their similar abilities, it is argued that non-human animals might be persons as well and should be granted more suitable rights. Linked to these animal rights are duties towards them that have a great affect on zoos and their moral justification. I will show that zoos have to fulfil certain criteria to suit today's zeitgeist and be morally defensible. The strongest justification is conservation as I will explain.