The Medical Dictionary for Regulatory Activities (MedDRA) version 2.0, agreed upon by the International Conference on Harmonisation, is a hierarchical medical terminology designed for use in both pre- and postmarketing phases of the medicines regulatory process. It covers diagnoses, symptoms, adverse drug reactions, therapeutic indications, investigation results, surgical and medical procedures, and medical/social history. MedDRA aims to improve data quality, support effective analysis, and facilitate electronic communication. The terminology is derived from sources like WHO-ART, COSTART, and ICD, and will be maintained by a Maintenance Support Services Organisation (MSSO). While it does not include definitions, it is expected to be the preferred terminology for international electronic regulatory communication.The Medical Dictionary for Regulatory Activities (MedDRA) version 2.0, agreed upon by the International Conference on Harmonisation, is a hierarchical medical terminology designed for use in both pre- and postmarketing phases of the medicines regulatory process. It covers diagnoses, symptoms, adverse drug reactions, therapeutic indications, investigation results, surgical and medical procedures, and medical/social history. MedDRA aims to improve data quality, support effective analysis, and facilitate electronic communication. The terminology is derived from sources like WHO-ART, COSTART, and ICD, and will be maintained by a Maintenance Support Services Organisation (MSSO). While it does not include definitions, it is expected to be the preferred terminology for international electronic regulatory communication.