Two events in tennis were contested at the 1904 Summer Olympics in St. Louis, United States. The competitions were held from Monday, August 29, 1904 to Monday, September 5, 1904.
The host nation won every medal awarded, which was unsurprising as only one foreign entrant competed. The sport, which had been open to women in its previous incarnation, was again restricted to only male competitors as the number of events shrank from 4 to 2 with the elimination of women's singles, and mixed doubles.
Tennis at the 1904 Summer Olympics Wikipedia
A total of 36 tennis players from 2 nations competed at the St. Louis Games: Germany (1)
United States (35)