LMSI may refer to:

• Laser Magnetic Storage International, a defunct Philips subsidiary
• Lockheed Martin Systems Integration – Owego
• Latin Mass Society of Ireland

• Tre-Castell
• Trecastelli
• Trecate railway station
• Trecator-SC
• Treccia d'oro
• Trecco bay
• Trece
• Trecella railway station
• Trece Martires, Cavite
• Trece Martires (disambiguation)
• Trecenas
• Trecento period
• Trecentosexagesimal
• Trece rosas
• Trecesson
• Trechiama
• Trechiamiotes
• Trechicomimus
• Trechiella
• Trechimorphus
• Trechinae
• Trechinotus
• Trechiotes
• Trechisibus
• Trechistus