1. A comparative statistical study of male and female addicts based on the clinical records of one hundred men and one hundred women admitted to the U. S. Public Health Service Hospital, Lexington, Ky., is presented.2. Statistically typical male and female addicts are described.3. The male addict is a prisoner patient and has a more serious antisocial record than the female addict who, in contrast to the male, enters the hospital voluntarily.4. The male addict begins the use of drugs through curiosity and association and is inclined to use more than one kind of narcotic drug, whereas, the female becomes addicted for the relief of some painful or distressing physical condition and generally confines herself to the use of morphine.