This is the Advisor's report on Hypoxyphilia, as it is currently called in DSM-IV, submitted at the request of the DSM-5 Paraphilias Subworkgroup of the Sexual and Gender Identity Disorders Workgroup. The background literature is reviewed together with information from the author's recent and as yet unpublished research derived from an internet survey of more than 100 living practitioners of this paraphilic activity. It is recommended that the term "asphyiophilia," already used in the literature, is preferable as there is little to indicate that the effects of oxygen deprivation per se are the primary motive for the behavior; rather, it is sexual arousal to restriction of breathing. It is properly regarded as a severe and potentially dangerous manifestation of Sexual Masochism which can result in physical harm or death and therefore should be identified as such, perhaps as a specifier. However, there is no good reason to identify it as a separate paraphilia though it should be named in the DSM-5 text as it is a well-recognized and unusual mode of death. Less severe forms of Sexual Masochism which do not threaten life or otherwise cause serious physical harm should not be regarded as mental disorders.