MEDI is the Medicinal Chemistry Division of the American Chemical Society. MEDI has about 9,600 members. The Division provides comprehensive programming at the twice annual National ACS meetings, as well as at the biennial National Medicinal Chemistry Symposium.
The MEDI Division was founded in 1909. You can read a history of the Division, written by Dr. Patrick Woster at the centennial of the Division in 2009.
You can become a member of MEDI and enjoy benefits including the annual publication Annual Reports in Medicinal Chemistry, an outstanding ~600 page volume providing timely and critical reviews of important topics in medicinal chemistry.
"The Division of Medicinal Chemistry and its members have been driving forces behind the discovery of revolutionary new medicinal agents and thus have had a major impact on human health."
The ACS website has information on careers in medicinal chemistry.