1978 U.S. Clay Court Championships – Men's singles

Manuel Orantes was the defending champion but lost in the semifinals to Jimmy Connors. Top-seed Connors claimed the title and first prize money of $24,000 by defeating seventh-seeded José Higueras in the final.

Seeds
A champion seed is indicated in bold text while text in italics indicates the round in which that seed was eliminated. • #🇺🇸 Jimmy Connors (champion)

• #🇦🇷 Guillermo Vilas (quarterfinals)

• #🇪🇸 Manuel Orantes (semifinals)

• #🇮🇹 Corrado Barazzutti (semifinals)

• #🇵🇱 Wojciech Fibak (withdrew — committee unaware)

• #🇺🇸 John McEnroe (quarterfinals)

• #🇪🇸 José Higueras (final)

• #🇦🇺 Ken Rosewall (first round)

• #🇬🇧 John Lloyd (first round)

• # Jaime Fillol (third round)

• #🇮🇹 Adriano Panatta (third round)

• #🇭🇺 Balázs Taróczy (third round)

• #🇦🇷 José Luis Clerc (third round)

• #🇳🇿 Chris Lewis (third round)

• # Hans Gildemeister (second round)

• #🇦🇺 Phil Dent (third round)