Weir has been dominant in the race over the past couple of years
Defending champion and four-time winner David Weir leads the field for the wheelchair races at the 2009 Flora London Marathon.
Weir claimed his third consecutive title last year in a sprint finish against Australian rival Kurt Fearnley.
"London is my home town, so it is nice to be among family and friends," said the 29-year-old.
Fearnley is among the contenders again this year, along with former winner Saul Mendoza of Mexico.
Mendoza triumphed in 2004 and 2005 and will be keen to return to the podium after a two-year absence from the race.
Other leading challengers include world record holder Heinz Frei of Switzerland, former winner Denis Lemeunier and leading South African Ernst van Dyk.
Weir has proved strong on his home course over the past three years and went on to take two gold medals in the 800m and 1500m races at the Beijing Paralympics but Fearnley triumphed in the marathon.
The women's field is also strong with Swiss duo Sandra Graf and Edith Hunkeler both entered along with American Amanda McGrory and Britain's Shelly Woods, who won the race in 2007.
Graf smashed the 11-year-old course record by more than a minute when she won last year but Hunkeler gained revenge in Beijing in a race where Woods just missed out on a medal.
"Last year was all about Beijing," she said. "Hopefully being able to focus on London will help in my overall performance. The London Marathon is special to me and there is nothing like racing at home."
Men's elite field: David Weir, Ernst van Dyk, Heinz Frei, Saul Mendoza, Kurt Fearnley, Masazumi Soejima, Denis Lemeunier, Rafael Botello Jimenez, Choke Yasuoka, Jose Antonio Inigues, Tomasz Hamelak, Joshua George.
Women's elite field: Sandra Graf, Amanda McGrory, Edith Hunkeler, Diane Roy, Shelly Woods, Christie Dawes.