On Earth, Williams has run marathons in about 3-1/2 hours.
Williams said in a media briefing early this month: "Just the fact that I'm running that much slower is going to be a little bit tedious because it's going to be a long time on the treadmill."
Race officials were not able to calculate her finishing spot immediately, but based on last year's results, she would be ranked at about 6,300th place among about 7,600 women runners.
Williams ran in steady 75 degree Fahrenheit (23.8 Celsius) temperatures in the still air of the space station.
She faced very different conditions from the frigid rain, 50 mph (80 kph) maximum wind gusts and 50 degree Fahrenheit (10 Celsius) temperatures handled by her earthbound competitors.
NASA astronaut completes Boston Marathon on orbit
Posted on Wednesday, April 18 2007 @ 11:25 CEST by Thomas De Maesschalck