LDT may stand for:
- Laboratory Developed Test, assays developed in the laboratory for internal use, intended for diagnostic or medical use.
- Labordatenträger, an xDT format to transfer orders of medical laboratory tests and their results.
- Laser Direct Testing, Beamind's technology to convert UV light from laser beams into electric current in a full non-contact way to test IC Package substrates and other complex HDI PCBs for opens and shorts
- Lateral dorsal tegmental nucleus, a nucleus of gray matter in the tegmentum
- Learning Design and Technology, an academic program focused on designing learning environments with emergent technologies
- Lexical decision task, a procedure used in many psychology and psycholinguistics experiments
- Lightning Data Transport, the old name of the HyperTransport computer bus
- Local Descriptor Table, an element of computer hardware
- LdT, Telbivudine (Tyzeka), a drug for the treatment of chronic hepatitis B
- Stanford LDT program, the Learning, Design and Technology program at Stanford University
- Light displacement ton, the weight of a ship without anything on board, used to determine the value of a ship which is to be scrapped
- LaDainian Tomlinson, a former running back
- Lymphocyte Doubling Time
- LeJOS Development Toolkit, an Eclipse plug-in for developing programs for the LeJOS environment on the Lego Mindstorms systems
- Let's Do This, A motivational statement/text-friendly acronym.
- Lejos Del Teclado, translation into Spanish of the Internet slang three-letter acronym AFK
- Large Diameter Tapcon