Salt consists of sodium and chloride, and is important for normal physiologic function. High sweat rates in athletes result in loss of both fluids and sodium. Fluid replacement with hypotonic solutions will lead to incomplete rehydration and possible complications such as hyponatremia, decreased performance, heat cramps, or other heat-related illness. There is significant individual variation in sodium loss during activity. In some the losses can be replaced by normal dietary intake, whereas in others the losses can be dramatic and increased dietary intake is essential. There are various methods to increase sodium intake, such as increased use of table salt on foods, salty snacks, adding salt to sports drinks, and use of salt tablets. Emphasis on replacement of fluids is also important, but care must be taken to avoid overhydration. Simple measures such as recording daily pre- and postexercise body weight can aid in making fluid and sodium ingestion decisions; in some cases, a comprehensive evaluation is necessary.