EMDEX (Essential Medicines InDEX) is the most commonly used reference source of drug and therapeutic information by healthcare professionals in Nigeria. It was first published in 1991 as Nigeria's Essential Drugs (NED) Guide.EMDEX drug information contents, arrangements and therapeutic recommendations are supported by several references and clinical guidelines notably WHO Model Formulary, WHO ATC (Anatomical Therapeutic Chemical) Classification System, Nigeria's Essential Medicines List and Standard Treatment Guidelines, etc. The information is regularly reviewed and updated by a select team of healthcare practitioners and academics.The central objective of EMDEX has been to promote rational use of medicines through provision of independent drug information, and use of clinical guidelines