LLI may refer to:
- Low latent inhibition(lli),A medical condition related to Latent inhibition which is concerned with the different observations that a stimulus adapts to.
- Langdons Language Institute, a language training facility Trinidad and Tobago.
- .LLI: Requested Top Level Domain for Leonese language.
- Lli (trigraph) : A trigraph used in French.
- Universal Wrestling Association: Lucha Libre Internacional.
- Unequal leg length or Leg length inequality (LLI).