| 1931 South American Championships in Athletics | |
| Host City: | Buenos Aires, Argentina |
| Dates: | 30 April–5 May |
| Previous: | Lima 1929 |
| Next: | Montevideo 1931 (U) |
The 1931 South American Championships in Athletics were held in Buenos Aires, Argentina between 5 April and 5 May.
| 100 metres | Carlos Bianchi Lutti | 10.9 | José de Almeida | 11.0 | Juan Piña | ||
| 200 metres | Carlos Bianchi Lutti | 21.9 =CR | Juan Piña | 22.2 | José Vicente Salinas | ||
| 400 metres | José Vicente Salinas | 49.6 | Héctor Domínguez | 49.8 | Ernesto Riveros | ||
| 800 metres | Hermenegildo Del Rosso | 1:58.6 | Leopoldo Ledesma | 1:59.6 | Alfredo Narváez | ||
| 1500 metres | Leopoldo Ledesma | 4:05.8 | Hermenegildo Del Rosso | 4:07.0 | Ernesto Medel | 4:09.6 | |
| 3000 metres | Luis Oliva | 8:46.8 CR | Belisario Alarcón | 8:47.0 | Juan Carlos Zabala | 8:48.2 | |
| 5000 metres | José Ribas | 15:04.8 CR | Juan Carlos Zabala | 15:11.6 | Belisario Alarcón | 15:16.6 | |
| 10,000 metres | Juan Carlos Zabala | 31:19.0 CR | José Ribas | 31:26.8 | Belisario Alarcón | 32:19.6 | |
| 110 metres hurdles | Miguel Aldatz | 15.6 | Armando Sorucco | 15.6 | Valerio Vallanía | ||
| 400 metres hurdles | Sylvio Padilha | 54.8 CR | Carlos dos Reis | 55.6 | Carlos Müller | 56.0 | |
| 4 × 100 metres relay | Juan Bautista Pina Daniel Hermida Rodolfo Borzino Carlos Bianchi Lutti | 43.0 | José de Almeida Mario Marques Arnaldo Ferrara Ibere Reis da Silva | 43.6 | Jaime Cardoso Ricardo La Rosa José La Rosa Jaime Meregalli | ||
| 4 × 400 metres relay | R. Salinas Guillermo Soto Ernesto Riveros José Vicente Salinas | 3:25.2 | José Signoris Leonidas Payal Alzua Juan Acosta Roberto Genta | 3:25.8 | Sylvio Padilha Carlos Reis Filho Ibere Reis da Silva Domingos Puglisi | 3:28.2 | |
| 3000 metres team race | | | | ||||
| Cross country | Fernando Cicarelli | 45:51.0 | Humberto Delgado | 45:52.2 | Jorge Donoso | 46:13.0 | |
| High jump | Valerio Vallanía | 1.85 | Alfonso Burgos | 1.85 | Alberto Estrada | 1.80 | |
| Pole vault | Diego Pajmaevich | 3.70 | Adolfo Schlegel | 3.70 | Carlos Joel Nelli | 3.70 | |
| Long jump | Héctor Berra | 6.97 CR | Ciro Falcão | 6.91 | Juan Moura | 6.69 | |
| Triple jump | Luis Brunetto | 14.23 | Pedro Aizcorbe | 13.64 | Ricardo Mendiburo | 13.63 | |
| Shot put | Héctor Benapres | 13.39 CR | Juan Conrads | 13.38 | Rodolfo Butori | 13.36 | |
| Discus throw | Héctor Benapres | 44.30 CR | Armando Peloursson | 41.39 | Bento Barros | 40.59 | |
| Hammer throw | Pedro Goic | 46.50 | Federico Kleger | 45.57 | Alfredo Wismer | 45.44 | |
| Javelin throw | Joaquim da Silva | 55.74 CR | Efraín Santibáñez | 55.58 | José Pergañeda | 54.96 | |
| Decathlon | Héctor Berra | 7065.62 CR | Armando Sorucco | 6962.9 | Carlos Woebcken | 6591.19 |