LR or Lr may refer to:
In computer science, LR parsers are a type of bottom-up parser that efficiently read deterministic context-free languages, in guaranteed linear time.
LRRIQ3 (Leucine-rich repeats and IQ motif containing 3), which is also known as LRRC44, is a protein that in humans is encoded by the LRRIQ3 gene.
LRC (short for LyRiCs) is a computer file format that synchronizes song lyrics with an audio file, such as MP3, Vorbis or MIDI.
Low-density lipoprotein receptor-related protein 5 is a protein that in humans is encoded by the LRP5 gene.
Leucine-rich repeat kinase 2 (LRRK2), also known as dardarin (from the Basque word "dardara" which means trembling), is an enzyme that in humans is encoded by the PARK8 gene.