The Pseudeurotiaceae, a new family of cleistothecial Ascomycetes, is established. Members of this family are characterized by nonostiolate ascocarps which are frequently dark in color, irregularly disposed asci, and hyaline or brown ascospores which lack germ pores. The conidia are usually borne on simple phialides or sympodulae. Cryptendoxyla, Hapsidospora, Leuconeurospora, Mycoarachis, and Nigrosabulum are described as new genera and included in the Pseudeurotiaceae. A key to the genera of the Pseudeurotiaceae is also given and some comments are offered on the previously established genera.