Concussions remain one of the most troublesome injuries sports physicians face. Studies suggest recovery takes hours to weeks, but at what point is the concussed brain no longer at increased risk for reinjury is unknown. Physicians must be alert to the symptoms of concussion and be familiar with the available tools to assess neurocognitive dysfunction. Prospectively validated signs and symptoms include amnesia, loss of consciousness, headache, dizziness, blurred vision, attention deficit, memory, postural instability, and nausea. A player with any signs or symptoms of a concussion should not be allowed to return to the current game or practice and should be monitored closely for deterioration of symptoms. Return-to-play should be individually based and proceed in a step-wise manner. The ongoing risk-benefit analysis of return-to-play must currently be based on experience, corollary data from traumatic brain injuries in animals and humans, and limited prospective data with sports-related concussions.