1978 South American Championships – Singles

Guillermo Vilas was the defending champion but did not compete that year.

José Luis Clerc won in the final 6–4, 6–4 against Víctor Pecci.

Seeds
A champion seed is indicated in bold text while text in italics indicates the round in which that seed was eliminated.


 * 1) 🇮🇹 Corrado Barazzutti (semifinals)
 * 2) 🇺🇸 Harold Solomon (semifinals)
 * 3) 🇪🇸 José Higueras (quarterfinals)
 * 4) 🇦🇷 José Luis Clerc (champion)
 * 5)  Hans Gildemeister (first round)
 * 6) 🇮🇹 Paolo Bertolucci (second round)
 * 7)  Jaime Fillol (first round)
 * 8) 🇳🇿 Chris Lewis (quarterfinals)