And on Monday, the now 70-year-old ran the marathon again, wearing the same bib number, but under very different circumstances.
"I finished, like I did 50 years ago", Switzer posted on Facebook after completing Monday's race.
On Sunday, Geoffrey Kirui managed to win the 121st Boston Marathon as Kenyans dominated the men's as well as females' races.
The longest distance women were allowed to run in the Olympics at that time was 800 meters.
In 1967, Kathrine Switzer became the first woman to officially run the Boston Marathon by using her initials, K.V. Switzer, to secure a bib.
Eliud Kipchoge, the runner's fellow countryman, who grasped Olympic gold in 2008, also boasted the same extraordinary muscle definition. He ran his first Marathon in Washington D.C.in 2015 and finished Boston a year ago as well.More news: Chicago Bulls' rebounding prowess will cause Boston Celtics problems all series
In 1963 two women crashed the Western Hemisphere Marathon in Culver City, Calif., and one finished.
Switzer and her coach pored through the rules and regulations about the Boston Marathon and couldn't find anything about gender.
On Monday, she reached her goal by crossing the Boston Marathon finish line in a time of 4:49:25.
"It's not for me, it's for others to be inspired, to be motivated", he said after he completed the race. I had long hair, wore lipstick and eyeliner to the start line.
"I turned to Arnie and said, 'I'm going to finish this race on my hands and my knees if I have to, '" she said.
This isn't Granville's first marathon either - he used a hand-bike to compete in marathons in Boston, Chicago, Detroit and NY despite his injury but didn't use a bike this time around.