Parricidal themes are cited from the historical, mythological, and psychoanalytic literature. Characteristics of the adult perpetrator and the role of the victim are discussed in relation to two cases illustrating successful intervention. There are 15 theories of interpersonal violence that relate to understanding intrafamilial violence categorized into intraindividual, social psychological, and sociocultural theories. The psychopathology and drugs and alcohol theories within the intra-individual theories category are particularly relevant to the dynamics associated with parricidal families, especially to adult members. Violence occurs because either some internal psychiatric abnormality in the individual or because the alcohol and drugs release violent underlying tendencies already present in the individual. Two in-depth, clinical cases of parricide involving perpetrators with mental illness and drug use, respectively, are described and analyzed to illustrate a number of factors which have been associated with parricide. A consideration of these factors as a group may prove useful in the identification of high risk cases and may lead to preventive intervention. 51 references (Author abstract modified)