Methamphetamine (METH) abuse has become a major public health problem worldwide, as demonstrated by increases in the number of emergency room visits, substance abuse treatment episodes, and arrests attributable to METH manufacture and abuse. However, there are currently no pharmacological treatments for the wide range of symptoms associated with METH abuse. One of the reasons for this problem is that our knowledge of the cellular and molecular mechanisms underlying the development of METH-induced psychosis and dependence is limited. This book presents a review of the recent findings on METH abuse in humans. First by describing the background and physiological effects of METH in humans. Next, by discussing the clinical findings on METH abusers derived using brain imaging techniques (single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance spectroscopy (MRS), and functional magnetic resonance imaging (fMRI)). Finally, by reviewing the potential therapeutic approaches for the treatment of METH abusers.