This study examines the disruption of ego in Sam Shepard’s A Lie of the Mind through the theories of Jacques Lacan. According to Lacan, the split-self of the main character is caused by the intervention of the ‘Symbolic Father,’ which prevents the declaration of the individual ‘I’ from escaping the dyadic relationship with its alter-ego. In this play, Jake’s father, who could take up the symbolic function, has always left, while his mother is so obsessed with Jake that he cannot construct his own subjectivity. With parents that fail to play their roles, Jake and Mike are victims of topsy-turvy families. The conflict between the two brothers, Jake and Frankie is viewed as a struggle between two split halves of the self. Although the character’s behavior in this play seems to repeat, Shepard means to reveal the course of how healthy identities are formed through the extreme cases of fragmented selves.