Goldenseal (Hydrastis canadensis L., Ranunculaceae) is an ingredient of various dietary supplements intended for enhancing general body immunity. Many goldenseal products are currently available in the United States, either alone or in combination with echinacea. In most products, the content of the main active alkaloids of goldenseal, hydrastine and berberine, is not indicated on the label. A high-performance liquid chromatography (HPLC) method has been developed for the detection and quantification of hydrastine and berberine in a number of products obtained from the United States market. The method uses a Phenomenex Luna C(18) column, a mobile phase consisting of solvent A (100 mM sodium acetate/acetic acid, pH 4.0) and solvent B (acetonitrile/methanol; 90/10, v/v). Elution was run at a flow rate of 1.0 mL/min, with a linear gradient of 80- 40% A in B over 20 min and ultraviolet detection at 290 nm. A wide range of content variation was observed for both alkaloids in the tested samples.