An operating theatre or operating room is a room within a hospital within which surgical operations are carried out.

Operating theatres were so-called in the United Kingdom because they traditionally consisted of semi-circular amphitheatres to allow students to observe the medical procedures.

The Old Operating Theatre in London is one of the oldest, dating back to 1822. It is a similar age to the Etherdome in Boston (1824).

Dissecting theatres also exist in Padua and Uppsala.