Methamphetamine (METH) is closely related chemically to amphetamine (AMPH). METH is a potent central nervous system stimulant with additional peripheral sympathomimetic effects. METH and AMPH have been used clinically in the treatment of obesity, minimal brain dysfunction, narcolepsy, depression and to counter fatigue. They are also subjected to widespread abuse. METH is an indirect agonists. It causes the release of newly synthesized norepinephrine and dopamine and it blocks the re uptake of these transmitters from the synapse. This can lead to an increase in the concentration of catecholamines in the synapse as well as an overall increase in catecholaminergic activity in the brain. The mechanism of METH induced neurotoxicity for all monoaminergic cell types may lie primarily with the dopaminergic system in the striatum. It may also lie with the interaction between METH induced release of dopamine and its ability to inhibit monoamine oxidase.