Two known fungal metabolites, macrophin and colletodiol, and a new stereoisomer of colletodiol named 10-epi-colletodiol, were isolated as immunosuppressive principles from an Ascomycete, Diplogelasinospora grovesii. The IC₅₀ values of the major active component among them, macrophin, were calculated to be 0.4 and 0.3μg/ml against concanavalin A- and lipopolysaccharide-induced proliferations of mouse spleen lymphocytes, respectively. A new natural product, 4, 8-dimethyl-1, 5-dioxacyclooctane-2, 6-dione, and a known fungal metabolite, isosclerone, which showed no immunosuppressive activity, were also isolated from this fungus.