There are apparently laws on the books dating back more than 150 years, when the Gopher State was just the Gopher Territory, making it illegal for a married woman to cheat on her husband, reports CBS station WCCO-TV in Minneapolis.
Another statute prohibits single women from having sex at all.
The law against married women is a gross misdemeanor and carries a prison sentence of one year, plus a possible fine of up to $3,000.
"It's completely obsolete and should be repealed," State Senator Ellen Anderson told WCCO.
Neither law is enforced, but not everyone thinks they're outdated.
"We think they're important. They send a message," said Tom Prichard of the Minnesota Family Council, who thinks the laws should actually be strengthened to apply to men as well.
"When you are dealing with a marriage, it's not just a private activity or a private institution. It's a very public institution. It has enormous consequences for the rest of society," Prichard said.
Anderson said most lawmakers won't bite on trying to repeal the sex laws - because they're not enforced, it may not be worth spending the political capital.
"Anything that has to do with sex for some reason becomes a political football around the Capitol."