Peculiar creeping or crawling sensations localized to the leg area between the knee and ankle constitute the syndrome denoted as "restless legs" The sensations appear when the limbs are at rest, and are worse at night. This paper presents data obtained on 175 cases, 72 men and 103 women. No neurologic abnormalities have been demonstrated and in most cases the syndrome is an independent disease of long duration. Though not psychogenic in nature, the pathogenesis is unknown. The symptoms are alleviated by vasodilator drugs, fever and movement and intensified by anemia and iron deficiencies. An accumulation of metabolites in the tissues may be a related cause.