The Centers for Disease Control (CDC) has said that hard-hitting ads featuring first-person stories from former smokers prompted more than 200,000 Americans to immediately give up tobacco.
Half that number are likely to stay off tobacco forever, according to the study that appeared in British medical journal The Lancet.
The CDC's $54 million media campaign in March-June 2012 dwelled on real-life stories from ex-smokers struggling with smoking-related illnesses and disabilities.
It was the first time a federal agency had developed and paid for advertisements aimed at getting people to abandon smoking.
"This is exciting news... I encourage anyone who tried to quit to keep trying -- it may take several attempts to succeed," said CDC director Tom Frieden.
Tim McAfee, head of the CDC's Office on Smoking and Health, called such ad campaigns "great investments" in public health.
The 2012 campaign prompted an estimated 1.6 million smokers to at least attempt to quit.
"The study shows that we save a year of life for less than $200," said McAfee in a statement. "That makes it one of the most cost-effective prevention efforts."
A second series of ads ran earlier this year, and a third round is set to go out in 2014.
Smoking is the leading cause of preventable death and disease in the United States, killing more than 1,200 Americans every day, according to the CDC.
More than eight million Americans live with a smoking-related disease which cost the nation $96 billion a year in direct health-care expenses and $97 billion in lost productivity.