Multiple-chemical sensitivity (MCS) is a condition in which individuals have an acute hypersensitivity to low levels of chemicals found in everyday substances, such as household cleaning agents, pesticides, fresh paint, new carpeting, synthetic building materials, newsprint, perfume, and numerous other petrochemical products. This condition continues to remain somewhat of a mystery to the medical community, and its true prevalence rate is unknown because many cases are not identified and reported as MCS. This article will inform the reader about the condition of MCS.