Clean room design is the method of copying a design by reverse engineering and then recreating it without infringing any of the copyrights and trade secrets associated with the original design. Clean room design is useful as a defense against infringement because it relies on independent invention. Because independent invention is not a defense against patents, clean room designs typically cannot be used to circumvent patent restrictions.

The term implies that the design team works in an environment that is 'clean', or demonstrably uncontaminated by any knowledge of the proprietary techniques used by the competitor.

Typically, a clean room design is done by having someone examine the system to be reimplemented and having this person write a specification. This specification is then reviewed by a lawyer to ensure that no copyrighted material is included. The specification is then implemented by a team with no connection to the original examiners.

A famous example is that of Compaq who built the first clone of an IBM computer through a clean room implementation of its BIOS.

Clean room design is also known as the Chinese wall technique.

The term clean room used on its own has a different meaning in the field of integrated circuit manufacture.