Pain resulting from disease involving the sensory roots of the spinal nerves is frequently encountered in neurologic practice. The diagnoses made in 100 consecutive cases of root pain that I have observed attest the importance of the disease processes which produce this symptom. It is gratifying to note that in the majority of cases the pain is the result of protruded intervertebral disks or extramedullary tumors of the spinal cord, conditions in which brilliant therapeutic results are obtained in most instances. I realize that radicular pain is not frequently encountered by physicians who are not neurologists, yet this condition must be considered in the differential diagnosis of a host of ordinary diseases. Fortunately, root pain has characteristics as definite as the pain of angina pectoris, pleurisy, peptic ulcer, arthritis and biliary colic, with which it is sometimes confused. The recognition of the characteristics of root pain directs the clinical search