An unprecedented 138 major U.S. companies scored 100 percent in a Corporate Equality Index compiled by the Human Rights Campaign, a Washington-based gay rights advocacy group.

That number was up from 101 companies last year and was 10 times higher than the 13 companies with that score in 2002, said the campaign, which conducts research and education programs and lobbies Congress.

Top companies offer such benefits as medical coverage and family leave to same-sex partners, prohibit discrimination against transgender workers or advertise in ways that respect gays, lesbians, bisexuals and transgender people, it said.

"More companies are not only implementing very comprehensive workplace policies that cover gay employees and their families but more companies are doing it faster and also seeking recognition for it," said Daryl Herrschaft, director of the group's workplace project.

Consistent high scorers since the group began the index in 2002 have been IBM Corp., Citigroup, J.P. Morgan Chase & Co.,Levi Strauss & Co and Nike Inc., he said.

"I think corporations are responding to a basic American value that has served them well for hundreds of years, that does not change with the political winds," Herrschaft said. "That is giving everybody equal opportunity at work, and making them feel like valued employees is not only the right thing but it's also good for the bottom line."

Research shows gay and lesbian consumers spend some $641 billion a year, he said. Also, gays and lesbians are likely to pay attention to workplace policies, are brand-loyal and have higher amounts of disposable income, Herrschaft said.

The campaign looked at 1,520 companies from such lists as the Fortune 1000 and Standard & Poor's 500 and culled enough information to rank 446 on its index.

Three companies scored zero -- Exxon Mobil Corp., Midwestern retailer Meijer Inc. and Plano, Texas-based Perot Systems technology consultants.

None offered minimal benefits or workplace protection for gay employees, the campaign said.

Representatives of Exxon Mobil, Meijer and Perot Systems did not return calls seeking comment.