High levels of cholesterol do not predict the risk of stroke in women, according to researchers in Denmark.
They did detect an increased risk in men, but only when cholesterol was at almost twice the average level.
The report in Annals of Neurology recommends using a different type of fat in the blood, non-fasting triglycerides, to measure the risk.
The Stroke Association said triglyceride tests needed to become routine to reduce the risk of stroke.
A total of 150,000 people have a stroke in the UK each year. Most are ischemic strokes, in which a clot in an artery disrupts the brain's blood supply.
The research followed 13,951 men and women, who took part in the Copenhagen City Heart Study.
During the 33-year study, 837 men and 837 women had strokes.
They reported that the cholesterol levels in women were not associated with stroke, while there was only an association in men with levels higher than 9mmol/litre. The average in UK men is 5.5.
The researchers at Copenhagen University Hospital said this was "difficult to explain" as LDL, or bad, cholesterol is known to cause atherosclerosis which can block arteries.
They did notice a link, in both men and women, between the risk of stroke and non-fasting triglycerides.
They believe these fats are a marker for "remnant cholesterol" which is left behind when other forms of cholesterol are made.
Dr Peter Coleman, deputy director of research at The Stroke Association said: "Tests for triglyceride levels aren't routinely carried out in the UK unless there is significant concern."
"We know that high levels of fats, such as cholesterol, increase your risk of having a stroke. However, this research shows the importance of measuring the fat triglyceride, as well as cholesterol.
"This study highlights the importance of measuring triglycerides routinely in order to reduce a person's risk of stroke."