| Doubles | |
|---|---|
| 2004 Western & Southern Financial Group Masters | |
| Champions |  Mark Knowles  Daniel Nestor |
| Runners-up |  Jonas Björkman  Todd Woodbridge |
| Final score | 6–2, 3–6, 6–3 |
Bob and Mike Bryan were the defending champions, but lost in second round to Jonathan Erlich and Andy Ram.
Mark Knowles and Daniel Nestor won the title, defeating Jonas Björkman and Todd Woodbridge 6–2, 3–6, 6–3 in the final.
All seeds received a bye into the second round.
Jonas Björkman / Todd Woodbridge (final)
Bob Bryan / Mike Bryan (second round) Mark Knowles / Daniel Nestor (champions)
Michaël Llodra / Fabrice Santoro (quarterfinals)
Wayne Black / Kevin Ullyett (second round) Wayne Arthurs / Paul Hanley (second round)
Martin Damm / Cyril Suk (second round)
Mahesh Bhupathi / Leander Paes (quarterfinals)| Semifinals | Final | ||||||||||||
| 1 | Jonas Björkman Todd Woodbridge | 6 | 6 | ||||||||||
| Jared Palmer Pavel Vízner | 3 | 4 | |||||||||||
| 1 | Jonas Björkman Todd Woodbridge | 2 | 6 | 3 | |||||||||
| 3 | Mark Knowles Daniel Nestor | 6 | 3 | 6 | |||||||||
| 3 | Mark Knowles Daniel Nestor | 6 | 4 | 79 | |||||||||
 Max Mirnyi  Sargis Sargsian | 4 | 6 | 67 | ||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | J Björkman T Woodbridge | 7 | 6 | ||||||||||||||||||||||||
 F López T Robredo | 6 | 6 | F López T Robredo | 5 | 3 | ||||||||||||||||||||||
| J Novák P Pála | 3 | 2 | 1 | J Björkman T Woodbridge | 6 | 64 | 7 | ||||||||||||||||||||
 J Knowle  N Zimonjić | 66 | 5 |  F González N Massú | 3 | 77 | 5 | |||||||||||||||||||||
| F González N Massú | 78 | 7 | F González N Massú | 6 | 3 | 6 | |||||||||||||||||||||
| 7 | M Damm C Suk | 4 | 6 | 3 | |||||||||||||||||||||||
| 1 | J Björkman T Woodbridge | 6 | 6 | ||||||||||||||||||||||||
| J Palmer P Vízner | 3 | 4 | |||||||||||||||||||||||||
| 4 | M Llodra F Santoro | 6 | 7 | ||||||||||||||||||||||||
| A Clément S Grosjean | 77 | 4 | 2 |  R Schüttler  M Youzhny | 2 | 5 | |||||||||||||||||||||
| R Schüttler M Youzhny | 64 | 6 | 6 | 4 | M Llodra F Santoro | 1 | 3 | ||||||||||||||||||||
| WC | J Kerr J Thomas | 66 | 7 | 3 | J Palmer P Vízner | 6 | 6 | ||||||||||||||||||||
| J Palmer P Vízner | 78 | 5 | 6 | J Palmer P Vízner | 64 | 77 | 77 | ||||||||||||||||||||
| 6 | W Arthurs P Hanley | 77 | 64 | 63 | |||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 8 | M Bhupathi L Paes | 66 | 77 | 7 | |||||||||||||||||||||||
| F Čermák L Friedl | 6 | 3 | 7 | F Čermák L Friedl | 78 | 64 | 5 | ||||||||||||||||||||
 C Haggard  X Malisse | 2 | 6 | 5 | 8 | M Bhupathi L Paes | 3 | 4 | ||||||||||||||||||||
 D Hrbatý  A Pavel | 6 | 3 | 79 | 3 | M Knowles D Nestor | 6 | 6 | ||||||||||||||||||||
 G Etlis M Rodríguez | 3 | 6 | 67 | D Hrbatý A Pavel | 6 | 2 | 3 | ||||||||||||||||||||
| 3 | M Knowles D Nestor | 4 | 6 | 6 | |||||||||||||||||||||||
| 3 | M Knowles D Nestor | 6 | 4 | 79 | |||||||||||||||||||||||
| M Mirnyi S Sargsian | 4 | 6 | 67 | ||||||||||||||||||||||||
| 5 | W Black K Ullyett | 65 | 3 | ||||||||||||||||||||||||
| Alt | A Bogomolov Jr. D Tursunov | 4 | 3 | M Mirnyi S Sargsian | 77 | 6 | |||||||||||||||||||||
| M Mirnyi S Sargsian | 6 | 6 | M Mirnyi S Sargsian | 77 | 6 | ||||||||||||||||||||||
| WC | R Ginepri J Morrison | 3 | 4 |  J Erlich A Ram | 61 | 3 | |||||||||||||||||||||
| J Erlich A Ram | 6 | 6 | J Erlich A Ram | 6 | 5 | 7 | |||||||||||||||||||||
| 2 | B Bryan M Bryan | 4 | 7 | 5 | |||||||||||||||||||||||
Michaël Llodra and Fabrice Santoro were the defending champions, but they lost in quarterfinals 6–7(2), 5–7, against Jonas Björkman and Max Mirnyi.
Jonas Björkman and Todd Woodbridge were the defending champions, but lost in the third round to Leander Paes and David Rikl.
The 2003 Canada Masters doubles was the men's doubles event of the one hundred and fourteenth edition of the Canada Masters; a WTA Tier I tournament and the most prestigious men's tennis tournament held in Canada. Bob Bryan and Mike Bryan were the defending champions but lost in the semifinals to Jonas Björkman and Todd Woodbridge. Mahesh Bhupathi and Max Mirnyi won in the final 6–3, 7–6(7–4) against Björkman and Woodbridge.
Jonas Björkman and Todd Woodbridge were the defending champions, but lost in the second round to Tomáš Cibulec and Daniel Vacek.
Wayne Ferreira and Yevgeny Kafelnikov were the defending champions but lost in the first round to Mark Knowles and Daniel Nestor.
Jonas Björkman and Todd Woodbridge were the defending champions but lost in the final 6–2, 6–4 against Mahesh Bhupathi and Jan-Michael Gambill.
Mark Knowles and Daniel Nestor were the defending champions but lost in the quarterfinals to Leander Paes and David Rikl.
Mark Knowles and Daniel Nestor were the defending champions but lost in the quarterfinals to Roger Federer and Max Mirnyi.
James Blake and Todd Martin were the defending champions but lost in the second round to Wayne Arthurs and Paul Hanley.
Mark Knowles and Daniel Nestor were the defending champions but lost in the quarterfinals to Wayne Black and Kevin Ullyett.
Paul Hanley and Nathan Healey were the defending champions but they competed with different partners that year, Hanley with Wayne Arthurs and Healey with Jordan Kerr.
Roger Federer and Max Mirnyi were the defending champions but only Mirnyi competed that year with Mahesh Bhupathi.
Jonas Björkman and Todd Woodbridge were the defending champions, but did not participate together this year. Björkman partnered Max Mirnyi, losing in the first round. Woodbridge retired from professional tennis earlier in the year.
Wayne Arthurs and Paul Hanley were the defending champions, but lost in the first round this year.
Arnaud Clément and Sébastien Grosjean were the defending champions, but did not partner together this year. Clément partnered Jaroslav Levinský, losing in the first round. Grosjean partnered Gaël Monfils, losing in the second round.
Mahesh Bhupathi and Max Mirnyi were the defending champions, but lost in the quarterfinals to Michaël Llodra and Fabrice Santoro.
Donald Johnson and Jared Palmer were the defending champions, but lost in the semifinals to Jonas Björkman and Todd Woodbridge.
Mark Knowles and Daniel Nestor were the defending champions, but lost in Quarterfinals to Wayne Black and Kevin Ullyett.
Wayne Black and Kevin Ullyett were the defending champions, but lost in second round to Mario Ančić and Ivan Ljubičić.
Mahesh Bhupathi and Max Mirnyi were the defending champions, but played this tournament with different partners. Bhupathi teamed up with Todd Woodbridge while Mirnyi teamed up with Jonas Björkman. Both pairs were eliminated in semifinals.