CAMBRIDGE, Mass. (Reuters) - Hundreds of workers at Harvard University's dining halls voted on Wednesday to accept a contract that raises their pay, ending a three-week-long strike, the university's first in more than three decades.

More than 700 workers at the Ivy League school's dining halls walked off the job on Oct. 5, saying that full-time workers who were employed year round deserved an annual salary of $35,000. They will return to work on Thursday, the UNITE HERE Local 26 union that represents them said in a statement.

The union and Harvard, whose $35.7 billion endowment is the largest of any U.S. university, reached a final contract proposal which the union's bargaining committee tentatively approved on Tuesday.

The five-year deal also holds the workers health care costs steady for the contract period.

"We accomplished everything," the union said in a statement following the vote.

Harvard Executive Vice President Katie Lapp said the agreement met the workers' requests while recognizing "the importance of carefully stewarding university finances as we pursue our academic mission in a period of constrained resources."

U.S. universities have increasingly been the target of organizing campaigns with unions starting to represent graduate students, adjunct faculty and other university staff who have not enjoyed the same degree of pay and benefits afforded to tenured professors.

During the strike, workers staged regular protests in Harvard Square, a popular tourist destination just outside Boston, through the strike, with their numbers occasionally boosted by students who joined in their protests.

The university pointed out throughout the strike that its dining hall staff were paid more than the average food service worker in the greater Boston area.

The 380-year-old school's leafy campus remains open all year round, attracting large numbers of visiting foreign students through the summer.

The agreement comes less than a week after a union representing some 5,500 professors at 14 Pennsylvania public universities ended a three-day strike after reaching a deal in which the university system agreed to pay raises.

(Reporting by Scott Malone; Editing by Andrew Hay and Alistair Bell)