The survey, conducted by researchers at Baylor University in Waco, Texas, asked 350 questions about religion to 1,648 adults across the country.
Fifty-five percent said they believed they were protected from harm by a guardian angel, a figure that researcher Christopher Bader said came as a surprise.
"To find out that more than half of the American public believes this was shocking to me. I did not expect that," he said.
Sixty-seven percent said they were "absolutely sure" heaven exists and 17 percent believed it "probably" does. Seventy-three percent of Americans believe in hell, it found.
Women are more likely than men to believe in heaven (68 percent to 56 percent), blacks more than whites (86 percent to 60 percent), southerners more than easterners (76 percent to 50 percent).
Also, political party was linked to religious beliefs, with 77 percent of Republicans saying they believed in heaven, compared to 54 percent of Democrats.
Those Americans who say they do not believe in God -- four percent -- as well as those who say they have no religion -- 11 percent -- were very close the figures in the 2005 survey.
In all 45 percent of Americans say they have had at least two religious encounters in their lives, the survey found, and conservative Protestants were more likely than Catholics or Jews to report religious or mystical experiences.