A novel 19-nor-neo-clerodane derivative, teucorymbin, and three known neo-clerodanes (19-acetylgnaphalin, teucjaponin A and 6-acetylteucjaponin B) were isolated from the aerial parts of Teucrium corymbosum. The structure of teucorymbin [18-acetoxy-5α,6-epoxy-6-oxo-19-nor-neo-cleroda-4α,3(16),14-trien-20,12S-olide] was established by chemical and spectroscopic means.