(Adds details from protest)

By Jim Young and Justin Madden

OAK BROOK, Ill., May 25 (Reuters) - Hundreds of protesters marched through pouring rain to call for higher wages and union rights at McDonald's Corp on Wednesday, leading the hamburger chain to shut down its headquarters a day before its annual meeting.

The suburban Chicago campus was shut for the third year in a row because of protests centered on the shareholder gathering, which will be on Thursday. The marchers are part of a larger U.S. movement for higher pay that, along with an improved economy, has spurred pay rises at companies ranging from Wal-Mart Stores to McDonald's own company-owned restaurants.

McDonald's restaurant employees and supporters seeking a $15-an-hour minimum wage and better benefits marched about two blocks in the downpour to the headquarters.

"If we don't get it, shut it down," they chanted. A Reuters witness estimated that there were up to a thousand protesters, though an accurate count was difficult because of the weather.

After the march, many scattered while others set up dozens of small tents on the street in front of the McDonald's building. Police watched from company property and there was no sign of violence.

McDonald's encouraged employees to work from home on Wednesday and Thursday, spokeswoman Lisa McComb said in an email.

The "Fight for $15" campaign, which is backed by the Service Employees International Union, since 2012 has had a hand in convincing some lawmakers and big employers to boost minimum wages and improve working conditions. The union represents workers ranging from fast-food restaurants to home health aides.

Last July, McDonald's raised average hourly pay and began offering paid vacations and other benefits for the roughly 90,000 workers at its company-operated U.S. restaurants.

"At McDonald's, we take seriously our role in helping strengthen communities," providing many with their very first job," McComb said.

As one of the world's largest and most recognizable companies, McDonald's is the target of frequent protests. It says it cannot tell its franchisees how to pay their employees. Almost 90 percent of McDonald's 14,000 U.S. restaurants are operated by franchisees.

McDonald's worker Adriana Alvarez, 24, of Chicago, said employees had been given three raises in one year at her franchisee-owned restaurant, a change for the good. She makes $10.50 an hour and came out to protest for the third year in a row, fueled by her desire to give her 4-year-old son, Manny, a better future.

"The fact that you have to choose paying your light bill or eating is ridiculous," she said standing on a flat bed truck and soaked from the rain.