The 1975 Louisville Open, also known as the First National Tennis Classic, was a men's tennis tournament played on outdoor clay courts at the Louisville Tennis Center in Louisville, Kentucky in the United States. It was the sixth edition of the tournament and was held from July 28 through August 5, 1975. The tournament was part of the Grand Prix tennis circuit and categorized in Group AA. The singles final was delayed by one day due to rain and was won by defending champion Guillermo Vilas who received the $16,000 first prize money. The doubles final was not played due to rain and the prize money was shared.[1] [2] [3]
Guillermo Vilas defeated 
Ilie Năstase 6–4, 6–3
Wojciech Fibak / Guillermo Vilas and 
Anand Amritraj / Vijay Amritraj not played