The clinical presentation, symptoms, and signs in 20 new patients with the painful legs and moving toes syndrome are presented. Painful legs and moving toes may develop in the setting of spinal cord and cauda equina trauma, lumbar root lesions, injuries to bony or soft tissues of the feet, and peripheral neuropathy. In 4 of the 20 cases in the present study, no definite cause was found. Pain preceded the onset of toe movements in 18 cases, but in 2 the reverse sequence occurred. The pain had many of the characteristics of causalgia, but none of the patients exhibited the full picture of reflex sympathetic dystrophy, and peripheral trauma was the trigger in only 5 cases. Several patients reported that the occurrence of toe movements was closely related to the pain, although abolition of pain with lumbar sympathetic blocks was not necessarily associated with disappearance of the movements. Several features suggest a central origin for the movements. Symptoms may begin on one side and become bilateral; movements may be momentarily suppressed by voluntary action or exacerbated by changing posture; and electromyography reveals complex patterns of rhythmic activity with normal recruitment of motor units involving several myotomes. Three other patients with similar moving toes but no pain are also described. The occurrence of similar movements in the absence of pain raises the possibility that these cases represent examples at one end of a spectrum of disorders, with pain alone (causalgia) at the other end and the syndrome of painful legs and moving toes in between.(ABSTRACT TRUNCATED AT 250 WORDS)