Some 1,200 fewer people were admitted to hospital with heart attacks during the first year of the smoking ban in England.
Experts believe some 200 deaths may have been prevented by the legislation in this period, and the fall in emergency admissions saved the NHS around £8.4 million, they said.
Each year around 141,000 people in the UK suffer a myocardial infarction, or heart attack. Around a third die, usually before they reach hospital.
The survival rate in hospital is 85%, so within a group of 1,200 admitted patients around 180 would be expected to die.
Study leader Dr Anna Gilmore, director of the Tobacco Control Research Group at the University of Bath, said: "Given the large number of heart attacks in this country each year, even a relatively small reduction has important public health benefits.
"This study provides further evidence of the benefits of smoke-free legislation."
She added: "Long term, we would expect to see further reductions in heart attacks, based on what we know about the effects of second-hand smoke."
Smoking in public places and working environments was made illegal in England on 1 July 2007.
England's smoking ban followed others introduced earlier in Scotland, Wales and Northern Ireland.