Fractionation guided by immunomodulatory activity of the EtOAc extract of the Ascomycete Eupenicillium crustaceum has afforded two new naturally occurring products, 4'-oxomacrophorin D (1) and 4'-oxomacrophorin A (2), as the immunosuppressive components of this fungus [1: 3-hydroxy-3-methylglutaryl (HMG) conjugate of 2]. The structures including the absolute configurations of 1 and 2 have been determined on the basis of chemical correlation of 1 with macrophorin D (3). The absolute configuration of the HMG moiety in 3 has been revised from 3R to 3S.