 Metal Organic Frameworks, MOFs, have been investigated extensively for use in biomedical applications due to their unique properties such as high surface area, porosity, and tunable pore size. These features make them ideal candidates for drug delivery, protein and nucleic acid encapsulation and intracellular delivery. Recently, several strategies have been developed to functionalize MOFs with therapeutic agents including surface adsorption, pore encapsulation, covalent binding, and functional molecules as building blocks. The most recent biological applications of MOFs include intracellular delivery of drugs, proteins, and nucleic acids, particularly aptomers. Challenges and prospects are also discussed to provide context for future development of MOFs as efficient drug delivery systems. This article was authored by UJS Sun, Li Weijing, Yu Yang, and others.