Immunomodulatory activity-guided fractionation of the ethyl acetate extract of an Ascomycete, Sordaria gondaensis, afforded three dioxopiperazine-type constituents as the immunosuppressive features of this fungus. They were elucidated to be two known fungal metabolites, tryprostatin B and fumitremorgin B, and a new metabolite 13-oxofumitremorgin B by their physicochemical and spectral data and the chemical correlation. This is the first time that both tryprostatin B and fumitremorgin B have been isolated from this fungus.