A reversed-phase HPLC procedure is proposed for the determination of seven flavonoids (luteolin, nepetin, hispidulin, jaceosidin, cirsimaritin, cirsilineol, and eupatorin) in vervain samples. A simple extractive technique was developed, involving only extraction with ethyl ether, which allowed the elimination of phenolic acids, yielding a sufficiently purified flavonoid fraction. All of the analyzed vervain samples showed a common flavonoid pattern, in which hispidulin and jaceosidin were the major compounds and nepetin was the minor compound.