Ten species of Hypomyces (Ascomycotina, Hypocreales, Hypocreaceae) occur on members of the Boletaceae) (Basidiomycotina, Agaricales). Five new species, viz. H. badius, H. boletiphagus, H. chlorinigenus, H. melanochlorus, and H. microspermus are described. One new combination, H. completus, is made. All species have a proven (five species) or associated (five species) anamorph referable to Sepedonium. The five species grown in culture from isolated ascospores produced hyphomycetous synanamorphs, and synanamorphs have been detected in collections of the other five species.