Abuse of amphetamines administered intravenously has become a well established and extensive form of drug abuse. The abuse potential of these drugs when taken by the intravenous route is greater than when taken orally and is comparable to that of heroin or cocaine. Tolerance builds rapidly and an abstinence syndrome develops which leads to a typical pattern in which the user takes the drug continuously and in immense doses for about five days during which he does not sleep. During this time he gradually becomes more paranoid and disorganized. He then desists for a day or two and falls into a prolonged semicomatose state. Upon awakening he is still lethargic and feels the need to resume his drug for a new round.