:1909 U.S. National Championships (tennis)

{{One source|date=May 2021}}

{{Use mdy dates|date=July 2023}}

{{Use American English|date=July 2023}}

{{TennisEventInfo|1909|U.S. National Championships|

| date =August 17–27 (M)
June 21–27 (W)

| edition = 29th

| category = Grand Slam

| location = Newport, R.I., United States (M)
Philadelphia, PA, United States (W)

| surface = Grass

| champms={{flagicon|USA}} William Larned{{cite book|author=Bud Collins|title=The Bud Collins History of Tennis|year=2010|publisher=New Chapter Press|location=[New York]|isbn=978-0942257700|pages=454–483|edition=2nd}}

| champws={{flagicon|USA}} Hazel Hotchkiss

| champmd={{flagicon|USA}} Fred Alexander / {{flagicon|USA}} Harold Hackett

| champwd={{flagicon|USA}} Hazel Hotchkiss / {{flagicon|USA}} Edith Rotch

| champxd={{flagicon|USA}} Hazel Hotchkiss / {{flagicon|USA}} Wallace F. Johnson

}}

File:Tennis Players on Newport Casino Court 1909.jpg

List of champions of the 1909 U.S. National Championships tennis tournament (now known as the US Open). The men's tournament was held from August 17 to August 27 on the outdoor grass courts at the Newport Casino in Newport, Rhode Island. The women's tournament was held from June 21 to June 27 on the outdoor grass courts at the Philadelphia Cricket Club in Philadelphia, Pennsylvania. It was the 29th U.S. National Championships and the second Grand Slam tournament of the three played that year.