Erotic asphyxiation (variously called asphyxiophilia, hypoxyphilia or breath control play) is the intentional restriction of oxygen to the brain for the purposes of sexual arousal. With a partner (or alone), the act often involves strangulation. The term autoerotic asphyxiation is used when the act is done by a person to themself. Colloquially, a person engaging in the activity is sometimes called a gasper. Erotic asphyxiation can lead to accidental death due to asphyxia.

The erotic interest in asphyxiation is classified as a paraphilia in the Diagnostic and Statistical Manual of the American Psychiatric Association.

Practitioners describe a number of physiological responses including "pleasurable sensations/euphoria (81.7%), a head rush (43.8%), feeling like they could not breathe (43.0%), difficulty swallowing (38.9%), unable to speak (37.6%), and watery eyes (37.2%). About 15% had noticed neck bruising and 3% had lost consciousness from being choked."

The practice of autoerotic asphyxiation has been documented since the early 17th century. It was first used as a treatment for erectile dysfunction. The idea for this most likely came from subjects who were executed by hanging. Observers at public hangings noted that male victims developed an erection, sometimes remaining after death (a death erection), and occasionally ejaculated when being hanged.

Various methods are used to achieve the level of oxygen depletion needed, such as a hanging, suffocation with a plastic bag over the head, self-strangulation such as with a ligature, gas or volatile solvents, chest compression, or some combination of these. Complicated devices (such as hydraulics) are sometimes used to produce the desired effects. The practice can be dangerous even if performed with care and has resulted in a significant number of accidental deaths. Uva (1995) writes "Estimates of the mortality rate of autoerotic asphyxia range from 250 to 1000 deaths per year in the United States." Cases have also been reported in Scandinavia and Germany. Swedish police reported in 1994 that the number of autoerotic asphyxiation fatalities in the Stockholm area (c. 1.7 million inhabitants) were at least five annually, but the number of unrecorded cases was assumed to be high. Autoerotic asphyxiation may often be mistaken for suicide, which is a major cause of death in teenagers.

In a 2021 survey of US students, women and transgender/nonbinary/gender nonconforming individuals are more likely to have been choked during sex than men.

Deaths often occur when the loss of consciousness caused by partial asphyxia leads to loss of control over the means of strangulation, resulting in continued asphyxia and death. While often asphyxiophilia is incorporated into sex with a partner, others enjoy this behaviour by themselves, making it potentially more difficult to get out of dangerous situations.

In some fatality cases, the body of the asphyxiophiliac individual is discovered naked or with genitalia in hand, with pornographic material or sex toys present, or with evidence of having orgasmed prior to death. Bodies found at the scene of an accidental death often show evidence of other paraphilic activities, such as fetishistic cross-dressing and masochism. In cases involving teenagers at home, families may disturb the scene by "sanitizing" it, removing evidence of paraphilic activity. This can have the consequence of making the death appear to be a deliberate suicide, rather than an accident.