At its inception, psychoanalytic psychology heavily emphasized sexuality. Freud's ideas about the centrality of sexuality in development and in the etiology of psychopathology were accepted for many years by organized psychoanalysis and psychiatry. Modern psychoanalytic theory has replaced sexuality as an organizing concept with diverse paradigms and the field has fragmented as a result. Of the many theories that Freud posed about the role of sexuality in psychological functioning perhaps his most influential were those pertaining to the Oedipus complex. In this, the first article of a series on the psychodynamic aspects of human sexuality, Oedipal aggression in males is considered from a biopsychosocial perspective. Knowledge about sexual differentiation of the brain and sex differences in behavior resulting from research carried out after Freud's death suggests the need to revise Freud's ideas about the Oedipus complex.