Aversion therapy is a form of psychological treatment in which the patient is exposed to a stimulus while simultaneously being subjected to some form of discomfort. This conditioning is intended to cause the patient to associate the stimulus with unpleasant sensations with the intention of quelling the targeted (sometimes compulsive) behavior.

Aversion therapies can take many forms, for example: placing unpleasant-tasting substances on the fingernails to discourage nail-chewing; pairing the use of an emetic with the experience of alcohol; or pairing behavior with electric shocks of mild to higher intensities.

Aversion therapy, when used in a nonconsensual manner, is widely considered to be inhumane. At the Judge Rotenberg Educational Center, aversion therapy is used to perform behavior modification in students as part of the center's applied behavioral analysis program. The center has been condemned by the United Nations for torture.