Chaenothecopsis bitterfeldensis sp. nov. is described and illustrated from Bitterfeld amber dating back to at least 20 million years ago. There has been no previous report of the sporing perfect stage of any Ascomycota in amber. The fungus also represents the first fossil record of resinicolous fungi and of the Mycocaliciaceae. The fossilised specimen contains over 20 fruiting bodies arising from an extensive mycelium. There are also hundreds of detached ascospores, some of which had germinated before the resin was transformed into amber. The taxonomy and palaeontology of the fossil fungus is discussed and stages in its preservation are described. Also some general aspects in the biology of resinicolous Mycocaliciaceae are reviewed. The striking similarity of C. bitterfeldensis to some extant species from East Asia suggests that the present distribution of these fungi is a relict of an ancient Laurasian range.