Two newmetabolites, citreo-γ-pyrone and citreothiopyrane A, with interesting biological activity have been isolated from the mycelia of hybridstrainsKO 0201 and 0211 derivedfromPenicilliumcitreo-virideB. IFO6200 and 4692. Their structures have been elucidated based on their spectral data. In addition, their biological properties are also described. The structure of citreothiolactone previously