Gliorosein is an unusual dihyrobenzoquinone isolated from a strain of Gliocladium roseum reported by researchers at ICI, England in 1951. The structure of gliorosein was resolved by Vischer two years later as a then unique “hemiquinone”. The stereochemistry was resolved by Groves in 1966. Treatment of gliorosein by acid or base with heat converts gliorosein to its co-metabolite, aurantiogliocladium. Gliorosein exhibits weak to moderate antibacterial and antifungal activity, however lack of availability has impaired a more detailed understanding of its pharmacology.