A reversed-phase high-performance liquid chromatography/diode-array detector procedure is proposed for the determination of six phenolic compounds (caffeic acid, luteolin 7-O-glucoside, rosmarinic acid, apigenin, hispidulin, and cirsimaritin) in sage. The chromatographic separation was achieved using a reversed-phase Spherisorb ODS2 (5-microm particle size, 25.0 x 0.46 cm) column. Of the several extractive solvents assayed only ethyl ether, ethyl acetate, and acetone were able to extract all the compounds mentioned. Best resolution was obtained using a gradient of water/phosphoric acid (999:1) and acetonitrile. Ten samples cultivated in two experimental fields (1997-1999) were analyzed and the individual compounds quantified. Four commercially available samples were also analyzed and the results are discussed.