Dyadic death is the death of two or more closely related persons; it includes both suicide pacts and homicide-suicides. Double suicides and suicide pacts are extremely rare. It has been classically described in spouses and lovers. The case of a double and simultaneous suicide of 39-year old monozygotic male twins through violent means (run over by a train) is presented. Both had records of anabolic androgenic steroids use, one of them of anxiety-depressive disorder; the suicide was planned and a suicide note was left mentioning personal reasons. The context of the case and the results of the psychological autopsy are presented; it is compared with the profile described in the literature, and the relationship with anabolic androgenic steroids use and the possibility of psychotic disorder (folie a deux) is specially considered.