NLM logo

RCD (Read Codes) - Synopsis

Search RCD in the UMLS Metathesaurus
(requires a free UMLS license)

Web site

The Read Codes were developed by Dr. James Read. The U.K. National Health Service Centre for Coding and Classification (NHS CCC) acquired and now maintains the Read Codes.

Read Codes are a standard terminology for describing the care and treatment of patients.

Read Codes contain hundreds of thousands of terms, synonyms, and abbreviations covering all aspects of patient care including signs and symptoms, treatments and therapies, investigations, occupations, diagnoses, and drugs and appliances.

Read Codes are now known as Clinical Terms. Clinical Terms Version 3 (CTV3) has been merged with the Systematized Nomenclature of Medicine – Reference Terminology (SNOMED RT®), resulting in the creation of SNOMED – Clinical Terms (SNOMED CT®). For more information about SNOMED CT in the Metathesaurus, see the SNOMED CT source synopsis.

Read Codes are used by healthcare professionals in computerized information systems.

Update Frequency
Read Codes are updated in April and October.

Metathesaurus Update Frequency
Read Codes were last updated in the Metathesaurus in 2000.

Sites Consulted

  1. Frequently Asked Questions about Clinical Terms (The Read Codes) [Internet]. Leeds (UK): NHS Connecting for Health; c2010 [cited 2010 Mar 17]. Available from: