Anhydroepiophiobolin A is a dehydrated analogue of ophiobolin epimerised at the C6 position. Anhydroepiophiobolin A is the major terminal degradation product of ophiobolin A and is co-produced with other ophiobolins in many Bipolaris species. Prior to 1984, references to “anhydroophiobolin” almost certainly refer to anhydroepiophiobolin A as the epimerisation at C6 was not well recognised. Under controlled degradation conditions both anhydroepiophiobolin A and anhydroophiobolin A are observed, but the latter is a minor component readily epimerised to anhydroepiophiobolin A. Like all ophiobolins, anhydroepiophiobolin A possesses a broad biological profile with antibacterial, antifungal, antitumor, herbicidal and nematocidal activities.