LFI can stand for:
- Labour Friends of Israel, a lobby group within the British Labour Party
- League for the Fifth International, an international grouping of revolutionary Trotskyist organisations
- League for the Fourth International, a Trotskyist international organisation
- Leatherhead Food International or Leatherhead Food Research, an organisation based in Surrey, England
- Limited Feedback Interaction, a recording technique used primarily in the creation of improvised music
- Local File Inclusion, a type of vulnerability most often found on websites
- Logkiy Frontovoi Istrebitel, a fifth-generation Russian fighter aircraft project