The strength of modern medicine is its relentless quest for an elusive perfection. That quest requires that we examine our errors even more closely than our successes. It is for this reason that the case report of Flinn and Sherer ("Seizure After Exercise in the Heat: Recognizing Life-Threatening Hyponatremia," page 61) is so important. For it records a potential tragedy that was prevented by expeditious and appropriate medical care ((1))-care that conflicted with popular dogma. The timeworn understanding is that collapse during or after prolonged exercise is caused by heat exhaustion; heat exhaustion is caused by dehydration; both are prevented by inordinate fluid ingestion; and immediate treatment should be intravenous fluids. I have termed this traditional litany the "dehydration myth" ((2,3)). It has been relentlessly perpetuated, always in the guise of good science.