A lecture theatre is a large room used for instruction, typically at a college or university. Unlike a traditional classroom with a capacity normally between one and fifty, the capacity of lecture theatres is typically measured in the hundreds. Lecture theatres almost always have a pitched floor, so that those in the rear are sat higher than those at the front, allowing them to see the lecturer. The importance of lecture theatres is so significant that some schools of architecture have offered courses exclusively centered on their design.

A microphone and loudspeakers are common to help the lecturer be heard, and projection screens may be used for large displays. The acoustic properties of lecture theatres have been the subject of numerous international studies, some even antedating the use of electronic amplification.