Progress has been made toward understanding the physiological mechanisms that underlie Gulf War illness and identifying possible treatments, says a new report on Gulf War Veterans' Illnesses, a condition that affects as many as 250,000 veterans of the 1990-91 Gulf War. Gulf War illness refers to the chronic symptoms that affect veterans of that conflict at markedly elevated rates, compared to other veterans' groups and to the U.S. population as a whole. Symptoms can vary from person to person, but typically include some combination of widespread pain, headache, persistent problems with memory and thinking, fatigue, breathing problems, stomach and intestinal symptoms, and skin abnormalities.