The New York Times Fiction Best Sellers of 2003
This is a list of adult fiction books that topped The New York Times Fiction Best Seller list in 2003. The Da Vinci Code dominated the year, spending a cumulative 20 weeks at the top. Sales continued strong into 2004.
| Date | Book | Author |
| January 5 | Prey | Michael Crichton |
| January 12 | The Lovely Bones | Alice Sebold |
| January 19 | The Lovely Bones | Alice Sebold |
| January 26 | Crossroads of Twilight | Robert Jordan |
| February 2 | Crossroads of Twilight | Robert Jordan |
| February 9 | The Lovely Bones | Alice Sebold |
| February 16 | The Lovely Bones | Alice Sebold |
| February 23 | The King of Torts | John Grisham |
| March 2 | The King of Torts | John Grisham |
| March 9 | The King of Torts | John Grisham |
| March 16 | The King of Torts | John Grisham |
| March 23 | The Jester | James Patterson and Andrew Gross |
| March 30 | The King of Torts | John Grisham |
| April 6 | The Da Vinci Code | Dan Brown |
| April 13 | The Da Vinci Code | Dan Brown |
| April 20 | Birthright | Nora Roberts |
| April 27 | Armageddon | Tim LaHaye and Jerry B. Jenkins |
| May 4 | Armageddon | Tim LaHaye and Jerry B. Jenkins |
| May 11 | Armageddon | Tim LaHaye and Jerry B. Jenkins |
| May 18 | Armageddon | Tim LaHaye and Jerry B. Jenkins |
| May 25 | Armageddon | Tim LaHaye and Jerry B. Jenkins |
| June 1 | Naked Prey | John Sandford |
| June 8 | The Da Vinci Code | Dan Brown |
| June 15 | The Da Vinci Code | Dan Brown |
| June 22 | The Da Vinci Code | Dan Brown |
| June 29 | The Lake House | James Patterson |
| July 6 | The Da Vinci Code | Dan Brown |
| July 13 | The Da Vinci Code | Dan Brown |
| July 20 | Johnny Angel | Danielle Steel |
| July 27 | The Da Vinci Code | Dan Brown |
| August 3 | To the Nines | Janet Evanovich |
| August 10 | The Da Vinci Code | Dan Brown |
| August 17 | The Da Vinci Code | Dan Brown |
| August 24 | The Da Vinci Code | Dan Brown |
| August 31 | The Teeth of the Tiger | Tom Clancy |
| September 7 | The Teeth of the Tiger | Tom Clancy |
| September 14 | The Da Vinci Code | Dan Brown |
| September 21 | The Da Vinci Code | Dan Brown |
| September 28 | Bleachers | John Grisham |
| October 5 | Bleachers | John Grisham |
| October 12 | The Five People You Meet in Heaven | Mitch Albom |
| October 19 | The Five People You Meet in Heaven | Mitch Albom |
| October 26 | The Five People You Meet in Heaven | Mitch Albom |
| November 2 | Blow Fly | Patricia Cornwell |
| November 9 | The Five People You Meet in Heaven | Mitch Albom |
| November 16 | The Da Vinci Code | Dan Brown |
| November 23 | The Da Vinci Code | Dan Brown |
| November 30 | The Da Vinci Code | Dan Brown |
| December 7 | The Da Vinci Code | Dan Brown |
| December 14 | The Da Vinci Code | Dan Brown |
| December 21 | The Da Vinci Code | Dan Brown |
| December 28 | The Da Vinci Code | Dan Brown |