Exxon says it will begin offering benefits to legally married same-sex couples in the U.S. for the first time as of Oct. 1.

The company says it will recognize "all legal marriages" when it determines eligibility for health care plans for the company's 77,000 employees and retirees in the U.S.

That means if a gay employee has been married in a state or country where gay marriage is legal, his or her spouse will be eligible for benefits with Exxon starting next year.

Exxon Mobil Corp., which is facing a same-sex discrimination lawsuit in Illinois, said Friday it was following the lead of the U.S. government. In June, the U.S. Supreme Court struck down the Defense of Marriage Act, which allowed states to refuse to recognize same-sex marriages granted in other states. And in recent months, federal agencies have begun to offer benefits to legally-married same sex couples.

"We haven't changed our eligibility criteria. It has always been to follow the federal definition and it will continue to follow the federal definition," said Exxon spokesman Alan Jeffers in an interview.