Pain in the back is the most common single reason given for occupational disability, and it is generally ascribed to actual injury to the vertebral column. The workman does not have to have any witnesses; he may neglect to report an occurrence to his employer, or he may think back to some indefinite date within one year to establish the basis for a claim of a work injury. An individual educated in legal and medical matters by such an experience may become a repeater, and for some this becomes a way of life. None of the rheumatic diseases have ever been created by slight or severe mechanical trauma in experimental animals or human beings. Many improbable medical decisions have been made by lay commissions in ignorance or disregard of this fact. It is believed that closer study and more precise diagnosis of back complaints will alter the statistics in this branch of occupational medicine.