A study found that patients with the debilitating condition experienced significantly less fatigue after eating 45 grammes of a special dark chocolate for eight weeks.
And when they were later given a placebo version without key ingredients they reported worse symptoms.
The condition, also known as ME, is little understood but as many as 250,000 people in the UK suffer from it.
Since the condition has no known cure or treatment, the chocolate discovery is a welcome intervention.
Experts believe chocolate could have a significant impact on neurotransmitters, which help to regulate mood and sleep.
The formulated chocolate used in the study in Hull, East Yorks., contained 85 per cent cocoa solids and was rich in polyphenol flavonoids - which also reduce the risk of death from coronary heart disease, cancer and stroke.
Prof Steve Atkin of Hull and East Yorkshire NHS Trust said: "No one has examined the effects of chocolate on chronic fatigue syndrome before so this is a very exciting result for us."
"We now hope to look at some of the other potential benefits of chocolate which is high in these natural chemicals."
The research is just the latest in a string of findings where the womens' favourite could help health problems. Other studies have pointed to improved brain function, reduction of blood pressure, pain relief, more stamina and stronger sex drive.
Chocolate could be the cure for chronic fatigue syndrome | the Daily Mail