The tree daturas, native to a number of localities in South America, are well-known as ornamental and to some extent as medicinal plants. Datura sanguinea, a red-flowered species, is found naturally in the Andes of Peru and Ecuador and was first described by Ruiz and Pavon (1799). Safford (1920, 1921) has described the local uses of this plant and distinguished a closely related species, D. rosei, which has saffron-coloured flowers and soft hairs clothing coarsely-toothed leaves. The structure of the leaves and stems of D. sanguinea has been described by Wallis and Konjovic (1963). Villalba, Medina and Albarracin (1945) examined the leaves, flowers and fruits of "borrachero rojo" (D. sanguinea) and were unable to characterise scopolamine; the principal alkaloid reported was atropine (0.345%). Drey and Foster (1953) analysed various organs of the plant by a paper chromatographic method and found scopolamine to be the predominant alkaloid in the aerial organs together with smaller amounts of hyoscyamine and atropine and some minor alkaloids, one of which had the same RF value as valeroidine. Other workers (Yoldi, 1958; Gertig, 1962) have also reported the principal alkaloid to be scopolamine with hyoscyamine in smaller quantity. In this paper we report, as part of a systematic study of the Section Brugmansia, the preliminary results of our investigation into the alkaloids of this species.