SLN may refer to:
- Dutch Sign Language
- Société Le Nickel, a French mining company
- solid lipid nanoparticles, a pharmaceutical delivery system
- Sri Lanka Navy
- The IATA code for Salina Municipal Airport in Salina, Kansas, United States
- Special linear group
- SYBYL Line Notation, a way of representing chemical structures
- Subscriber Line Number, the last four digits, or local number found in a local telephone numbering plan.
- A file name extension for Microsoft Visual Studio's SoLutioN file.
- A file name extension for Asterisk (PBX)'s Signed Linear audio file format