All Lincolnshire hospitals have now banned smoking on their grounds to try and reduce the effect of second-hand smoke.
Smoking was previously permitted in designated areas at hospitals in Lincoln, Boston, Grantham, and Louth.
The full smoking ban means that people can no longer smoke outside the hospitals from Monday, January 6, 2020.
Those who insist on smoking will not be obstructed but will be advised about the new policy and asked not to smoke on hospital grounds.
E-cigarettes and vaping will still be permitted within outdoor areas of the hospitals as long as it is not done in close proximity to others.
Stephen Kelly, from the United Lincolnshire Hospitals NHS Trust, said the hospitals have a duty for the health of patients, staff, and visitors.
He said: “Many of the people who use our services are particularly vulnerable to the harmful effects of second-hand smoke.
“We recognise that smoking is a personal choice and we do not discriminate against those who choose to do so, however, we are a health-promoting organisation.
“We are committed to protecting and improving the health and wellbeing of all employees, patients, and visitors.
“Being completely smokefree reflects our commitment and responsibility for improving health and wellbeing.”
During a four-week consultation, 56% of 801 people agreed that ULHT should go smoke-free.