By Guto Harri
BBC News, New York
Kentucky Fried Chicken has announced it will stop using trans-fatty acids for most of its products from next April.
Its biscuits, or scones, will still contain trans-fats, but the fast-food chain will not be frying food in them.
This comes as New York considers a ban on the use of trans-fats in the city's 20,000 restaurants.
With mounting concern about premature deaths and rising obesity in the US, trans-fat has become a number one target for campaigners.
If fast food is bad, trans-fat is evil. What it does is increase the damaging cholesterol content of a meal, clogging up arteries and increasing the risk of a heart attack.
They are partially hydrogenated vegetable oils, turning oily foods into semi-solid foods
Used to extend shelf life of products
Put into pastries, cakes, margarine and some fast foods
Can raise levels of "bad" cholesterol
Even a small reduction in consumption can cut heart disease
They have no nutritional benefit
Eighty percent of the items of a Kentucky Fried Chicken menu have it, so switching to a cleaner oil next April should have a significant impact.
Several hundred KFC outlets have been trying out alternative cooking oils for a while and the company says its customers have not been able to spot the difference.
The decision was announced as public hearings began in New York on a proposal to ban trans-fats from every restaurant in the city.
KFC's decision will apply to its outlets all over America, as is the case with the Wendy's chain which led the way on this over the summer.
McDonalds promised to reduce trans-fats in its products four years ago.
The company aims to roll-out a new cooking oil next year.