Kirui waved and smiled as he took the tape in a time of 2hr 9min 37sec, with Rupp finishing in second.
He pulled away from American Galen Rupp with about two miles to go to win in an unofficial time of 2 hours, 8 minutes, 37 seconds. It's the first time she's run the Boston Marathon since 1976 and her first marathon since 2011, but she's raced in 39 marathons throughout her lifetime and has a new prize waiting for her at the finish line this year. Times, luckily, have changed and women make up a large percentage of marathon runners. Suguru Osako of Japan came in third, followed by American Shadrack Biwott in fourth.
Finishing 13th, about eight minutes behind Rupp, was 2014 Boston champion Meb Keflezighi.
Back in 1967, women weren't allowed to run the Boston Marathon.
The warm temperatures that hit 79 degrees at the 20-kilometer mark in slowed the runners but the strong tailwind was a boost - especially for the wheelchair races. In his last competitive Boston run, he finished 13th in 2:17:00 despite pain in his quad muscles.
"After all the marathons I've run, this may be the most important of all", she said. This year, some of those the pack included a formerly homeless man who was running to raise money for a homeless shelter, and Ben Beach going for an unprecedented 50th straight Boston finish.
Hug outpushed 10-time victor Ernst Van Dyk of South Africa down Boylston Street to finish in an unofficial time of 1 hour, 18 minutes, 4 seconds.
The race has largely returned to normal four years after the bombing. "The roads were good".
Earlier Monday, city officials announced plans for memorials to mark the sites where two bombs exploded during the 2013 Boston Marathon.
Also in the field was Boston Police Commissioner William Evans, who ran for the 18th time in 2013 but has skipped the races since the bombings so he could be available in case of another emergency.
The 26.2-mile course goes through eight cities and towns, starting in Hopkinton and ending on Boylston Street in Boston.
"I'm at a point in my career where I feel like I can compete with anybody", he said this week.