38 cities with NPPES-registered healthcare providers in ON. Counts reflect providers with a ON practice address in the federal registry.
| Rank | City | Providers in ON |
|---|---|---|
| 1 | Toronto | 29 |
| 2 | London | 8 |
| 3 | Ottawa | 7 |
| 4 | Hamilton | 6 |
| 5 | Windsor | 6 |
| 6 | Kingston | 3 |
| 7 | Thornhill | 3 |
| 8 | North York | 3 |
| 9 | Markham | 3 |
| 10 | Lasalle | 2 |
| 11 | Sudbury | 2 |
| 12 | Mississauga | 2 |
| 13 | Leamington | 2 |
| 14 | Oshawa | 2 |
| 15 | Milton | 2 |
| 16 | Newmarket | 1 |
| 17 | White Lake | 1 |
| 18 | St Catharines | 1 |
| 19 | Shelburne | 1 |
| 20 | Quinte West | 1 |
| 21 | Toronto, Ontario | 1 |
| 22 | York | 1 |
| 23 | Stoney Creek | 1 |
| 24 | Toronton | 1 |
| 25 | Peterborough | 1 |
| 26 | Kitchener | 1 |
| 27 | Caledon | 1 |
| 28 | Hannon | 1 |
| 29 | Stoneycreek | 1 |
| 30 | St. Catharines | 1 |
| 31 | Scarborough | 1 |
| 32 | Tecumseh | 1 |
| 33 | Aurora | 1 |
| 34 | Etobicoke | 1 |
| 35 | Ancaster | 1 |
| 36 | Oakville | 1 |
| 37 | Sault Ste Marie | 1 |
| 38 | Ajax | 1 |