There is something irresistible about an infant monkey - they appear so sweet and helpless, and seem so much like a human infant in many ways. However, those sweet babies grow up into difficult adults, and as a general rule adult monkeys do not make good pets. Their intelligence makes them special, but ultimately makes them very challenging pets.
Note: this article was originally written about keeping monkeys as pets, but the issues are equally as important (possibly more) when it comes to apes (chimpanzees, orangutans, gibbons). Monkeys are a group of animals belonging to the order Primates (which of course, includes apes and humans) -- and the points made here can be applied to all non-human primates.
Taking on a pet monkey is a long term commitment. A well cared for monkey can live anywhere from 20-40 years, and needs your full commitment throughout their lives. A pet monkey cannot do without your attention when life gets busy or circumstances change.
Monkeys may not take well to new people in your life (including spouses and children), and make it hard to get away for vacations. Finding a new home for a pet monkey is extremely difficult, and very hard on the monkey which has bonded to its first owner.
Monkeys are expensive to house and feed, and some require specialized diets that can be time consuming to prepare. A significant commitment of time is needed just for routine care and cleaning up after a pet monkey, but more importantly a monkey needs a large amount of social interaction and attention from the owner. A pet monkey deprived of your time and attention will only develop severe behavior problems and psychological issues.
Primates including monkeys may be illegal to keep as pets in some areas. Many states prohibit keeping primates as pets. If legal, permits may be required, and sometimes permit holders are subject to inspection for proper facilities and care.
A wide range of diseases can be passed from monkeys and other primates to humans. See "Zoonoses Acquired from Pet Primates" by David M. Renquist, D.V.M., M.A. and Robert A. Whitney, Jr., D.V.M., M.S. for a thorough discussion of this aspect. Finding a vet who is able and willing to treat a primate may also be difficult. Monkeys and apes are also susceptible to a variety of illnesses of humans, which can be devastating for the monkey.
The sweet dependent baby monkey will eventually grow up, and become the wild animal it was meant to be. Unfortunately, raising a monkey around humans doesn't change the wild nature of monkey, and in fact depriving a pet monkey of normal social relationships with other monkeys can create behavior problems and neuroses.
Pet monkeys also have a tendency to bite. They have different personalities so one cannot generalize, but some monkeys will be very aggressive, and others will be more docile. Nevertheless, monkeys are unpredictable and may turn aggressively on anyone, including the person to whom they are the closest.
Monkeys are messy. They can't really be effectively toilet trained (many younger monkeys can be diapered or at least partly toilet trained, but that is often lost at maturity) and sometimes engage in distasteful activities involving their feces and urine.
Aside from the toileting messes, pet monkeys can be extremely mischievous and destructive, especially if bored.
Monkeys need a large secure enclosure and should spend time outdoors too if possible. They must be provided with a wide variety of ever changing toys and exercise equipment to keep them challenged and stimulated, or they will suffer from boredom.
There are many more aspects to cover in the consideration of monkeys as pets. For more detailed discussions of the reality of pet monkeys, visit the following web pages: