The prevalence of incest is noted, and demographic patterns are reported. Typical symptoms are discussed; for example, among adults incestuously abused as children, the problems most often encountered are sexual dysfunctions and difficulty with sexual contact. Additionally, periods of promiscuity or prostitution may result, and there is an increased risk of adolescent pregnancy. Other clinical symptoms among incest victims are depression, intense guilt, and drug/alcohol abuse. Incest victims tend to have marital difficulties, and there is an increased risk of their physically and emotionally abusing their children. Three persistent, negative effects of incest are explored: (1) chronic traumatic neurosis, with secondary elaborations resulting from lack of treatment; (2) continuing relational imbalances, with secondary elaborations resulting from lack of treatment; and (3) increased intergenerational risk. Reasons why no model of these negative effects has emerged are considered, and the most important reason is highlighted: the underlying negative effects do not emerge in any recognizable form until after disclosure of the incest. Victims rarely spontaneously disclose the incest, and therapists often do not ask for disclosure. Instead, former victims have a characteristic 'disguised presentation' for treatment, which is usually depression with complications and atypical impulsive and dissociative elements. Problems which can arise in treating incest victims are explored, and guidelines for the therapist are presented. Sixty references are provided.