Five former winners are set take their place in the women's elite field - defending champion from Ethiopia Worknesh Degefa, 2018 winner Desiree Linden from the United States, 2017 winner and double World Championship gold medallist Edna Kiplagat of Kenya, 2015 winner Caroline Rotich, also of Kenya and Ethiopian Buzunesh Deba, the 2014 course record holder.  

Challengers for the title are expected to include Mare Dibaba of Ethiopia, 2015 International Association of Athletics Federations (IAAF) World Championship gold medallist, who has previously finished second in this race.

Rose Chelimo of Bahrain is part of the line-up, having claimed both a silver and gold medal at the last two IAAF World Athletics Championship marathons at Doha in 2019 and London in 2017, respectively. 

Three-time Olympian Gelete Burka, is part of a strong Ethiopian contingent which also features two-time Olympian Meskerem Assefa, a winner of the Rotterdam and Frankfurt marathons, Yebrgual Melese, who has earned wins in marathons in Shanghai, Prague and Houston and three-time Rome Marathon champion Rahma Tusa. 

Returning to the race, part of the Abbott World Marathon Majors, are Canadian Krista Duchene, IAAF Half Marathon silver and bronze medallist Mary Ngugi of Kenya, and Kate Landau of the United States.

The field is completed by four debutants - the Kenyan trio of Magdalyne Masai, Besu Sado and Caroline Chepkoech Kipkirui and Ethiopian Haftamnesh Tesfay.

The men's elite field in Boston features four of the past five winners, including defending champion Lawrence Cherono of Kenya.

Cherono's competitors include Lelisa Desisa of Ethiopia, a two-time Boston winner, Yuki Kawauchi of Japan, the 2018 winner and 2017 IAAF World Championships gold medallist Geoffrey Kirui of Kenya, the winner of Boston in the same year.

Among their rivals are 2012 Olympic marathon champion and 2013 IAAF World Championship gold medallist Stephen Kiprotich of Uganda, Albert Korir of Kenya, and Ethiopian Dejene Debela, pipped by a single second by defending champion Cherono in last year's Chicago Marathon.

Returning to Boston are Kenyans Kenneth Kipkemoi, Philemon Rono, Benson Kipruto and Felix Kandie while Japanese duo Kentaro Nakamoto and Shoya Osaki are also part of the line-up.

Newcomers to the course include 2019 Frankfurt winner Fikre Bekele of Ethiopia and two-time Eritrean Olympian Abrar Osman while Ethiopian half-marathon record holder Jemal Yimer makes the step-up to 26 miles for the first time.

Completing the field are Dylan Wykes of Canada, Li Zicheng of China, Stephen Scullion of Ireland and Fernando Cabada of the United States.

In the women’s wheelchair race, Manuela Schär of Switzerland returns as defending champion.

Her previous victory in Boston came in 2017 when she became the first woman to go under the one hour 30 minute barrier.

Schar is set to be joined on the start line by five-time Boston champion Tatyana McFadden of the US and Madison De Rozario of Australia, who completed the podium in Boston last year.

Fellow Americans Susannah Scaroni, Amanda McGrory, and Katrina Gerhard and Australia’s Eliza Ault-Connell are other notable names in the field.

The men’s wheelchair field is led by defending champion Daniel Romanchuk of the US.

The 21-year-old became the youngest Boston Marathon wheelchair champion in history last year and is the first home winner in this category since 1993.

Four-time champion Marcel Hug of Switzerland and 10-time winner Ernst van Dyk of South Africa are expected to be among Romanchuk's challengers.

Fellow Boston winners Masazumi Soejima of Japan and former course record-holder Joshua Cassidy of Canada are also part of the field as well as British star David Weir, Spain’s Jorge Madera, and Japan’s Hiroki Nishida and Kota Hokinoue.

Fellow home hopefuls alongside Romanchuk are Aaron Pike, Joshua George, James Senbeta, Krige Schabort, and Hermin Garic.

"The Boston Marathon is proud to welcome the world’s best athletes each April, and this year’s race is no exception," Boston Athletic Association Tom Grilk said. 

"With Olympic and Paralympic medallists, national record holders, and rising stars, the race towards the finish line will be both fierce and exciting. 

"We look forward to crowning our 2020 champions on what will be another memorable Patriots’ Day."

Patriots Day is a public holiday across most of the US and the Boston Marathon has been run on this date since its inception in 1897.