The survey by the U.S. Centers for Disease Control and Prevention showed a stable pattern over recent years of Americans without health insurance -- numbers used as the basis for battles over healthcare and health insurance reform.
The CDC's National Center for Health Statistics said in its report that 15.4 percent of Americans lacked health insurance in 2009, compared to 14.7 percent in 2008.
The survey found that 46.3 million people had no health insurance in 2009, a bit up from 43.8 million in 2008. This included more than 6 million children under 18.
A U.S. healthcare overhaul passed in March would allow young adults to stay on their parents' plans longer and would require more Americans to buy health insurance.
Once fully implemented in 2014, the U.S. government projects, the new law will expand insurance coverage to 32 million uninsured Americans.
The CDC numbers differ slightly from the U.S. Census Bureau estimates, which are calculated using different data. The Census said in September that 46.3 million people in the United States lacked coverage in 2008.
But most Americans over the age of 65 are covered by Medicare, the federal health insurance plan for the elderly. The CDC found that 17.5 percent of people under 65 lacked health insurance in 2009, and 21 percent of adults aged 18 to 64.
A Harvard Medical School study published in September found that nearly 45,000 people die in the United States each year in large part because they lack health insurance and cannot get good care.
Some other facts from the survey, available at www.cdc.gov/nchs:
* 21 million people under 65 had public health plan cover, translating to 21 percent of that population.
* 14.4 million people over 65 and 37.7 million children had private insurance.
* 62.9 million people under 65 had private insurance in 2009, down from 65.4 million in 2008.
* 65.8 million over-65s had private health insurance, as did 55.7 million children
* Nearly 30 percent of young adults aged 18 to 24 lacked health insurance.
* Hispanics were the most likely to lack health insurance -- 30.7 percent had none.
(Reporting by Maggie Fox; Editing by Doina Chiacu.)