<jats:title>Abstract</jats:title><jats:sec id="S1368980004001156_sec01"><jats:title>Objectives:</jats:title><jats:p>To determine the relative quantities of two hepatotoxic pyrrolizidine alkaloids, symphytine and echimidine, in teas prepared from comfrey leaves (<jats:italic>Symphytum officinale</jats:italic>), and to determine the potential contribution of the<jats:italic>N</jats:italic>-oxide forms of these alkaloids to levels of the parent alkaloids.</jats:sec><jats:sec id="S1368980004001156_sec02"><jats:title>Design:</jats:title><jats:p>Comfrey leaves were purchased from three commercial sources and used to prepare tea in a manner consistent with the methods used by consumers. An extraction scheme was devised for extraction of the alkaloids, and a gas chromatographic method was developed to quantify the two major alkaloids, symphytine and echimidine. Recognising that the<jats:italic>N</jats:italic>-oxide derivatives of these alkaloids have also been identified in comfrey preparations, chemical reduction was applied to determine the total quantities of the alkaloids as free bases and as<jats:italic>N</jats:italic>-oxide derivatives.</jats:sec><jats:sec id="S1368980004001156_sec03"><jats:title>Results:</jats:title><jats:p>The concentration of symphytine and echimidine varied considerably between teas prepared from leaves purchased from the different vendors of plant material. Moreover, a much higher concentration of symphytine was found in the tea when steps were included to reduce<jats:italic>N</jats:italic>-oxides prior to analysis. The treatment of pure symphytine with hot water did not generate the<jats:italic>N</jats:italic>-oxide derivative<jats:italic>de novo</jats:italic>.</jats:sec><jats:sec id="S1368980004001156_sec04"><jats:title>Conclusions:</jats:title><jats:p>Since the pyrrolizidine alkaloids are known to be hepatotoxic, consumption of herbal teas made from comfrey leaves may be ill-advised. The concentration of pyrrolizidine alkaloids in such teas may be underestimated substantially unless the concentration of<jats:italic>N</jats:italic>-oxides is taken into consideration.</jats:sec>