Commensurate adsorption is an interesting and important phenomenon observed in sorption processes involving various types of sorbent materials such as zeolites. It is closely associated with (or related to) the crystal structure and symmetry, pore shape, size and topology of the adsorbent materials, and their compatibility with the gaseous adsorbates. This article will focus on recent development on commensurate adsorption of hydrocarbons in a new type of crystalline adsorbent materials, namely microporous metal-organic frameworks (MMOFs). Examples of different adsorbate/adsorbent systems will be reviewed and the origin of the phenomenon and its implications in separation will be discussed.