We recently reported (1) the isolation of the unsaturated pyrrolizidine alkaloid lycopsamine from leaves of borage (Borago officinalis L. Boraginaceae), a common garden herb used throughout the world in teas and salads. Also isolated was supinidine viridiflorate but only in trace amounts insufficient for determining optical rotation. (+)-Supinidine viridiflorate is named cynaustine; (-)-supinidine viridiflorate is amabiline (1) (2). Flowers of borage are used medicinally and in salads and beverages (3), while borage seed oil is known (3) to contain A-linolenic acid and could be used as a dietary supplement. We have now analyzed seeds, seed oil, and flowers for pyrrolizidine alkaloids. The only alkaloid found in the flowers and the major seed alkaloid was thesinine (2), the trans-p-hydroxycinnamate of (+)-isoretronecanol. This is a rare pyrrolizidine, having been found only once previously (4) from Thesium minkwitzianum. Mature seeds were found to contain 2 and a smaller amount of the same unsaturated pyrrolizidine as the leaves (1). A sufficient amount of the latter was isolated so that an optical rotation measurement could be obtained. The alkaloid proved to be amabiline (1) and not cynaustine. One bacch of immature seeds was also analyzed, and this material contained only thesinine. Three different samples ofborage seed oil were analyzed, and no alkaloids were found. Arnabiline was absent down to the 5 ppm level, but thesinine quantitation was too variable for low level determination. Unsaturated pyrrolizidines are suspect hepatotoxins (2), but saturated pyrrolizidines (such as the major seed component, thesinine) are not known to be toxic.Because no spectral data have been published for 2 and little for 1, 'H- and '3C-nmr data as well as physical properties are given below.