SNOMED (short for SNOMED Clinical Terms or SNOMED CT) is a set of medical terms used widely in clinical practice. Some have asked why CDISC develops its own Controlled Terminology, rather than using SNOMED. There are a number of reasons why we develop terminology:

• Use of SNOMED requires a license. Many governments have arranged licenses for users in their country, but there are still parts of the world where use of SNOMED is not free. CDISC Standards and Controlled Terminology are freely available to all users.
• Although SNOMED terms are in many ways well-documented, they do not have definitions. CDISC Controlled Terminology has definitions created under the direction of NCI-EVS .
• Regulatory agencies, as part of the International Conference on Harmonization, mandate MedDRA for coding adverse events.