| National Challenge Cup | |
| Year: | 1938 |
| Country: |  United States |
| Dates: | 16 January- 24 April 1938 |
| Defending Champions: | New York Americans |
| Winners: | Sparta Garden City |
| Count: | 1 |
| Second: | St. Mary's Celtic |
| Semifinal1: | Castle Shannon |
| Semifinal2: | New York Americans |
| Prev Season: | 1937 |
| Next Season: | 1939 |
The 1938 National Challenge Cup was the annual open cup held by the United States Football Association now known as the Lamar Hunt U.S. Open Cup. Scheduled as follows: First Round on or before January 16, Second Round on or before January 30, Quarterfinals February 13, Semifinals East February 26, 27, West February 20, 27.
a) aggregate after 3 games