Taken in small or moderate doses, amphetamines produce feelings of alertness, elation, confidence, anorexia, and insomnia, but severe effects occur as dosage increases, such as paranoia, acute anxiety, and hallucinations. Amphetamines have been misused since their introduction in the 1930's, especially during World War II, and the Korean and Vietnam wars when they were routinely issued to servicemen. The methedrine scene, which developed on the west coast in the late 1950's and early 1960's, was the first widespread use of injectable methamphetamine for its own effect. Legal prescriptions for the drug were readily available because it was viewed as a way to rehabilitate heroin addicts, and when legal sources were suppressed, illegal supplies were easy to manufacture. The speed scene in the Haight-Ashbury district of San Francisco shows how high dose amphetamine abuse within a criminalized subculture can produce extremely high levels of violence. Several research studies have examined the violence in Haight-Ashbury and observed that addicts resorted to high risk criminal activities to buy speed, became involved in manufacturing and dealing with their risks of theft and violence, or gradually switched to heroin to alleviate the adverse effects of amphetamines. Although the large centers of amphetamine use have dissipated, the use of large doses of this durg continues and has been linked to violence. In many cases, amphetamines appear to exacerbate poor impulse control or paranoid tendencies in persons who are socially maladjusted or have histories of deviant behavior. Case studies of three individuals convicted of homicides are analyzed to illustrate extreme examples of violent behavior in amphetamine abusers. After taking massive doses of oral amphetamines, all of these persons had become highly paranoid and delusional; although they knew such feelings could be drug-related, they were unable to recognize that their paranoid delusions were drug-induced. In conclusion, amphetamine abuse over extended periods contains great potential for unprovoked, random, and senseless violence, often in combination with other drugs and particularly by certain personality types. The article contains 13 references. (Author abstract modified)