Animals within zoo environments are learning continuously: they learn signals that predict when food is going to arrive or that the presence of a certain person means that something unpleasant may happen. They may learn to control their environment and caregivers: for example, they may learn that if they perform a particular behaviour (eg repetitive behaviour) they will receive a reward (ie food or attention from a caregiver). Using standard operant conditioning and classical conditioning techniques we can easily modify the behaviour of animals in zoos. Animals can be trained to comply with almost all minor veterinary procedures and examinations, such as injection, the measurement of heart rate, the cleaning of teeth and the treatment of superficial injuries. Compliance can be achieved using standard animal learning abilities without the need for punishment type I (ie physical punishment) or immobilisation (chemical or physical). In this paper we discuss how we apply learning theory to such procedures, the dangers associated with such programs (eg injury to the trainer) and the benefits (eg the treatment of large endangered animal species without the use of anaesthetic drugs). Additionally, we briefly discuss the selection and management of animal trainers. The methods we describe here are equally applicable to laboratory, farm and pet animals. Finally, as with all management processes applied to animals, a written policy on animal training needs to be produced by any institution training animals.