| Francisco Freire Allemão e Cysneiro | |
| Birth Date: | 24 June 1797 |
| Birth Place: | Rio de Janeiro, State of Brazil |
| Death Place: | Rio de Janeiro, Empire of Brazil |
| Fields: | Botany |
| Workplaces: | Brazilian National Museum |
| Alma Mater: | University of Paris |
| Author Abbrev Bot: | Allemão |
Francisco Freire Allemão e Cysneiro (24 June 1797 – 11 November 1874) was a Brazilian botanist who collected in northeast Brazil and along the Rio de Janeiro. His association with the Brazilian National Museum in Rio de Janeiro took place at a time when Brazilian botany was dominated by foreigners.
Among his many duties as physician of the Brazilian court was to fetch the Emperor's bride from Italy.
Some genera and species named by him: