The Handbook replaces the 'Clinical Memoranda on Economic Poisons,' which were first issued in March 1950 as separate releases on several new insecticides. Attention has been given to those materials that are manufactured in large amounts, that are known to have caused posioning relatively frequently, or that are of special interest for some other reason. Sections have been devoted to arsenic, thallium, phosphorus, and kerosene because they are leading causes of deaths associated with pesticides. The Handbook was prepared primarily for the guidance of physicians in the diagnosis and treatment of persons who may have had extensive or intensive exposure to economic poisons; however, it contains general information that may be of interest to others also.