1909 U.S. National Championships – Men's singles
# 1909 U.S. National Championships – Men's singles

Defending champion William Larned defeated William Clothier in the Challenge Round 6–1, 6–2, 5–7, 1–6, 6–1 to win the men's singles tennis title at the 1909 U.S. National Championships. Clothier defeated Maurice McLoughlin in the All Comers' Final.

The event was held at the Newport Casino in Newport, R.I. in the United States.

## Challenge round

| Challenge Round | Challenge Round | Challenge Round | Challenge Round | Challenge Round | Challenge Round | Challenge Round |
| - | - | - | - | - | - | - |
| William Larned | William Larned | 6 | 6 | 5 | 1 | 6 |
| William Clothier | William Clothier | 1 | 2 | 7 | 6 | 1 |

## All Comers' finals

| Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Finals | Finals | Finals | Finals | Finals | Finals |
| - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| William Clothier | William Clothier | 6 | 7 | 6 | | | | | | | | | | | | | | |
| Edward Whitney | Edward Whitney | 1 | 5 | 4 | | | | | | | | | | | | | | |
| Edward Whitney | Edward Whitney | 1 | 5 | 4 | | | William Clothier | William Clothier | 7 | 7 | 6 | | | | | | | |
| | | | | | | | Tom Bundy | Tom Bundy | 5 | 5 | 3 | | | | | | | |
| Tom Bundy | Tom Bundy | 6 | 7 | 6 | | | Tom Bundy | Tom Bundy | 5 | 5 | 3 | | | | | | | |
| William Cragin | William Cragin | 1 | 5 | 2 | | | | | | | | | | | | | | |
| William Cragin | William Cragin | 1 | 5 | 2 | | | | | | | | | William Clothier | William Clothier | 7 | 6 | 9 | 6 |
| | | | | | | | | | | | | | Maurice McLoughlin | Maurice McLoughlin | 5 | 4 | 11 | 3 |
| Richard Palmer | Richard Palmer | 5 | 4 | 2 | | | | | | | | | | | | | | | Maurice McLoughlin | Maurice McLoughlin | 5 | 4 | 11 | 3 |
| Maurice McLoughlin | Maurice McLoughlin | 7 | 6 | 6 | | | | | | | | | | | | | | |
| Maurice McLoughlin | Maurice McLoughlin | 7 | 6 | 6 | | | Maurice McLoughlin | Maurice McLoughlin | 6 | 4 | 7 | 6 | | | | | | |
| | | | | | | | Gus Touchard | Gus Touchard | 3 | 6 | 5 | 2 | | | | | | |
| Fred Inman | Fred Inman | 4 | 6 | 6 | 6 | 2 | Gus Touchard | Gus Touchard | 3 | 6 | 5 | 2 | | | | | | |
| Gus Touchard | Gus Touchard | 6 | 4 | 4 | 8 | 6 | | | | | | | | | | | | |
