Vogel, H. Facultad de Ciencias Agrarias, Universidad de Talca, Talca, Chile Razmilic, I. Instituto de Química de Recursos Naturales, Universidad de Talca, Talca, Chile Muñoz, M.; Doll, U. Facultad de Ciencias Forestales, Universidad de Talca, Talca, Chile Martin, J.M. Institute de Biología Vegetal y Biotecnología, Universidad de Talca, Talca, Chile.Boldo is a tree or shrub with medicinal properties native to Chile. The leaves contain alkaloids and essential oils. Variation of total alkaloid concentration, of the alkaloid boldine, and essential oil components were studied in different populations from northern, central, and southern parts of its geographic range and in their progenies (half-sib families). Total alkaloid concentration showed genetic variation between progenies of the central population but not between populations. Boldine content found in concentrations of 0.007 to 0.009% did not differ significantly between populations. Principal components of the essential oil were determined genetically, with highest values for ascaridole in the population of the north and for p-cymene in the south. Between half-sib families genetic variation was found in the central and northern populations for these components. The high heritability coefficients found indicate considerable potential for successful selection of individuals for these characters.