# 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.
* Corrado Barazzutti (semifinals)
* Harold Solomon (semifinals)
* José Higueras (quarterfinals)
* José Luis Clerc (champion)
* Hans Gildemeister (first round)
* Paolo Bertolucci (second round)
* Jaime Fillol (first round)
* Chris Lewis (quarterfinals)

## Draw
### Key

* Q = Qualifier
* WC = Wild card
* LL = Lucky loser
* Alt = Alternate
* SE = Special exempt
* PR = Protected ranking
* ITF = ITF entry
* JE = Junior exempt
* w/o = Walkover
* r = Retired
* d = Defaulted
* SR = Special ranking
| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| 1 | C Barazzutti | 6 | 6 | | | | | | | | | | | | | | | | | | | | |
| | B Prajoux | 4 | 0 | | 1 | C Barazzutti | 6 | 6 | | | | | | | | | | | | | | | |
| | P Cornejo | 3 | 6 | 2 | | H Varela | 4 | 4 | | | | | | | | | | | | | | | |
| | H Varela | 6 | 1 | 6 | | | | | | 1 | C Barazzutti | 6 | 6 | 6 | | | | | | | | | |
| | A Muñoz | 4 | 6 | 1 | | | | | | | C Kirmayr | 4 | 7 | 3 | | | | | | | | | |
| | C Kirmayr | 6 | 1 | 6 | | C Kirmayr | 7 | 6 | | | | | | | | | | | | | | | |
| | R Gehring | 6 | 2 | 6 | | R Gehring | 6 | 3 | | | | | | | | | | | | | | | |
| 7 | J Fillol | 3 | 6 | 2 | | | | | | | | | | | 1 | C Barazzutti | 4 | 4 | | | | | |
| 3 | J Higueras | 6 | 6 | | | | | | | | | | | | | V Pecci | 6 | 6 | | | | | |
| | P McNamee | 1 | 2 | | 3 | J Higueras | 6 | 6 | | | | | | | | | | | | | | | |
| | I Molina | 6 | 6 | 4 | | A Pattison | 4 | 2 | | | | | | | | | | | | | | | |
| | A Pattison | 4 | 7 | 6 | | | | | | 3 | J Higueras | | | | | | | | | | | | |
| | J L Damiani | 2 | 6 | 6 | | | | | | | V Pecci | w/o | | | | | | | | | | | |
| | P Dominguez | 6 | 2 | 1 | | J L Damiani | 3 | 6 | 1 | | | | | | | | | | | | | | |
| | V Pecci | 6 | 6 | | | V Pecci | 6 | 1 | 6 | | | | | | | | | | | | | | |
| 5 | H Gildemeister | 0 | 2 | | | | | | | | | | | | | | | | | | Víctor Pecci | 4 | 4 |
| 6 | P Bertolucci | 6 | 6 | | | | | | | | | | | | | | | | | 4 | José Luis Clerc | 6 | 6 |
| | F Dalla Fontana | 4 | 2 | | 6 | P Bertolucci | 6 | 2 | 6 | | | | | | | | | | | | | | |
| | A Maurer | 6 | 5 | 6 | | R Ycaza | 4 | 6 | 8 | | | | | | | | | | | | | | |
| | R Ycaza | 4 | 7 | 8 | | | | | | | R Ycaza | 3 | 3 | | | | | | | | | | |
| | W Zirngibl | 6 | 7 | | | | | | | 4 | J L Clerc | 6 | 6 | | | | | | | | | | |
| | G Barbosa | 3 | 5 | | | W Zirngibl | 1 | 1 | | | | | | | | | | | | | | | |
| | R Cano | 1 | 2 | | 4 | J L Clerc | 6 | 6 | | | | | | | | | | | | | | | |
| 4 | J L Clerc | 6 | 6 | | | | | | | | | | | | 4 | J L Clerc | 6 | 1 | 6 | | | | |
| 8 | C Lewis | 6 | 6 | | | | | | | | | | | | 2 | H Solomon | 2 | 6 | 2 | | | | |
| | G Hardie | 2 | 2 | | 8 | C Lewis | 5 | 6 | 6 | | | | | | | | | | | | | | |
| | J Andrew | 4 | 7 | 6 | | J Andrew | 7 | 0 | 2 | | | | | | | | | | | | | | |
| | L Álvarez | 6 | 5 | 1 | | | | | | 8 | C Lewis | 3 | 2 | | | | | | | | | | |
| | J Soares | 6 | 3 | 9 | | | | | | 2 | H Solomon | 6 | 6 | | | | | | | | | | |
| | P Kronk | 2 | 6 | 7 | | J Soares | 4 | 2 | | | | | | | | | | | | | | | |
| | V Winitsky | 6 | 4 | 4 | 2 | H Solomon | 6 | 6 | | | | | | | | | | | | | | | |
| 2 | H Solomon | 2 | 6 | 6 | | | | | | | | | | | | | | | | | | | |