The Mercury Drug Corporation, better known as Mercury Drug, is a Filipino pharmacy chain. A subsidiary of the Mercury Group of Companies, it is headquartered in Bagumbayan, Quezon City. The chain was founded in Santa Cruz, Manila in 1945, making it the second oldest drugstore chain in the Philippines after Southstar Drug. As of 2017, Mercury Drug has over 1,000 branches nationwide and over 50 percent of the Philippine pharmaceutical retail market.