While proper brain function requires the complex interaction of chemicals perpetually occupied in purposeful biochemistry, it is well established that certain toxic substances have the potential to disrupt normal brain physiology and to impair neurological homeostasis. As well as headache, cognitive dysfunction, memory disturbance, and other neurological signs and symptoms, disruption of brain function may also manifest as subtle or overt alteration in thoughts, moods, or behaviors. Over the last four decades, there has been the unprecedented development and release of a swelling repertoire of potentially toxic chemicals which have the capability to inflict brain compromise. Although the ability of xenobiotics to induce clinical illness is well established, the expanding public health problem of widespread toxicant exposure in the general population is a relatively new phenomenon that has spawned escalating concern. The emerging area of clinical care involving the assessment and management of accrued toxic substances such as heavy metals, pesticides, plasticizers and other endocrine disrupting or neurotoxic compounds has not been fully appreciated by the medical community and has yet to be incorporated into the clinical practice of many consultants or primary care practitioners.