The nationwide Harris poll of 1,010 adults found 56 percent of those surveyed were in favor of expanding current laws banning discrimination based on race, age, disability, religion and gender to include gay men and lesbians.
Thirty-four percent of respondents opposed such legislation and 11 percent refused to answer or said they did not know.
The results indicate increasing public acceptance of gays, Reuters reported. Two years ago, 52 percent were in favor of such anti-discrimination legislation and 41 percent opposed it.
The majority of states do not bar anti-gay discrimination and federal law does not ban employers from firing workers or landlords from refusing to rent to people because they are homosexual.
Fifteen percent of those surveyed said they approved of legalizing marriage between two men and 16 percent supported it for two women. Fifty-seven percent of respondents rejected it for men and 55 percent disapproved for women.
About one-quarter of those surveyed said they did not feel strongly about the issue and 2 percent to 4 percent refused to respond or said they did not know.
Still, the percentage approving same-sex marriage increased about 50 percent from four years ago. At that time, 11 percent supported it for women and 10 percent for men.
Adoption by gay couples was opposed strongly. Fifty-five percent and 57 percent disapproved of adoption by female and male couples respectively, while 22 percent and 21 percent approved. Almost 20 percent said they did not feel strongly about gay couples adopting.
The poll, conducted Jan. 6-10, did not use the term margin of error, but had a "statistical precision" of plus or minus 3 percentage points.