The systematic position of the fern genus Mesopteris is described and discussed based on its sol e species, M. tonkinensis. Evidence for its generic separation is based on its gross morphological characteristics, leaf epidermis, gametophyte development, spore morphology, and chromosome numbers. A morphological comparison with other related genera of Amphineuron, Cyclosorus, Dryopteris, Lasttea, and Thelypteris is provided.