A HPLC method with amperometric detection is established for the conta
ct allergen alpha-peroxyachifolid (1) from yarrow (Achillea millefoliu
m L., s. str.). The amounts of 1 are between 0.25 and 0.60 parts per t
housand in blossoms, dried 2 h at room temperature, and between 0.01 a
nd 0.05 parts per thousand in the leaves. In completely dried material
and in some preparations from the market 1 could also be quantified.