The study explored the sexual preferences of sexually sadistic males in terms of their consensual sexual relationships and examined the dynamics by which they introduced their partners into extreme and, at times, murderous forms of behavior. Previous research had shown that although sexually sadistic criminals were often forthcoming about their criminal and murderous behavior, they became descriptive and vague when describing the sexual fantasy and pattern of arousal that underlie these activities. The search for secondary sources of information, such as diaries, manuscripts, videos, and photographs that might further illustrate these preferences and fantasies resulted in the interviews summarized in this paper. The women interviewed reported early life experiences characterized by physical abuse and incestuous relationships; however, they achieved relatively stable and normal lifestyles before meeting and becoming involved with a sexually sadistic male. Once involved in a relationship with these sadistic men, the lives of the women changed radically and, in some instances, they voluntarily entered into dangerous forms of sexuality and criminal behavior. This paper's descriptions of these experiences highlight the relational context of the behaviors in which the sadistic fantasy of the male becomes an organizing principle in the behavior of the woman. The study concludes that the women's early experiences of physical, sexual, and incestuous abuse rendered them vulnerable to seduction by sexually sadistic men into sexual behaviors and forms of violence that were clearly outside their previous parameters of experience. In the most extreme cases of murder, the women would not have decided to perpetrate the murders independent of the men. Although issues of control and dominance characterize all battering relationships, in these sexually sadistic relationships, the themes of dominance, control, and humiliation have become eroticized and integrated into the sexual fantasy life and sexual arousal of the male. When law enforcement officers and forensic evaluators are faced with a sexually sadistic offender, they should explore the likelihood that the sexual behavior that has likely contributed to the crime has been enacted with the consensual partners of these men as well. Three brief case studies are presented. 2 tables and 9 references