Karyological characteristics of six Argentinian Astragalus species are reported: A. crucksh-anksii (2n=28), A. illinii (2n=28), A. neuquenensis (2n=28), A. moyanoi (2n=28), A. pehuenches (2n=22) and A. palenae var. grandiflora (2n=26). The x=13 and 14 species have bimodal complements but differ in chromosome morphology and asymmetry indices. All species have a single pair of chromosomes with satellites located on the long arms. A. pehuenches (2n=22, x=11) has a more symmetrical karyotype and a pair of SAT chromosomes with a satellite located on the short arms. Among the species with 2n=28, A. moyanoi has significantly greater DNA content than the rest. The species with the lowest chromosome number, A. pehuenches, has the highest DNA content. The members of species with 2n=28 studied in the present work are similar in both vegetative and reproductive morphology.Facultad de Ciencias Agrarias y ForestalesComisión de Investigaciones Científicas de la provincia de Buenos Aires