The PPS is now a well-recognized entity encompassing the late manifestations that occur because of previous poliomyelitis. Common signs and symptoms include fatigue, cold intolerance, joint deteriorations with pain, and prominent neurologic problems that include new weakness, muscle pain, atrophy, respiratory insufficiency, dysphagia, and sleep apnea. It is estimated that there are 1.63 million polio survivors in the United States and that half of them will develop PPS. PPS and PPMA usually begin 30 to 40 years after the acute illness and are very slowly progressive. The etiology is unclear, although premature exhaustion of the new sprouts that develop after acute poliomyelitis and of their motor neurons appears most likely. Less likely is a persistent polio-virus infection or an immune-mediated problem. Treatment is primarily supportive, although nonfatiguing strengthening exercise may improve strength over the short term. The long-term effects of this type of exercise remain to be clarified.