Medicinal chemistry or pharmaceutical chemistry is a discipline at the intersection of chemistry, pharmacology, and biology involved with designing, synthesizing and developing pharmaceutical drugs.

Medicinal chemistry involves the identification, synthesis and development of new chemical entities suitable for therapeutic use. It also includes the study of existing drugs, their biological properties, and their quantitative structure-activity relationships (QSAR). Pharmaceutical chemistry is focused on quality aspects of medicines and aims to assure fitness for the purpose of medicinal products. Medicinal chemistry is a highly interdisciplinary science combining organic chemistry with biochemistry, computational chemistry, pharmacology, pharmacognosy, molecular biology, statistics, and physical chemistry.

Many workers in the field do not have formal training in medicinal chemistry. A majority of working medicinal chemists have degrees in organic chemistry, rather than medicinal chemistry. Medicinal Chemistry is a multifaceted discipline that encompasses synthetic organic chemistry, natural products chemistry, enzymology, chemical biology, structural biology and computational methods, all of which are aimed at the discovery and development of new therapeutic agents. Scientists in the field are well positioned to work as part of an interdisciplinary team that uses chemical structural principles to design effective drugs and diagnostic agents. Graduate (Master's and Ph.D.) level programs in medicinal chemistry can be found in traditional medicinal chemistry departments, or in pharmaceutical sciences departments, both of which are traditionally associated with schools of pharmacy.