The population of Argentina is mostly composed of people of European ancestry. Aboriginal communities are at present very reduced in number and restricted to small geographically isolated patches. Three aboriginal communities, the Mapuche, Tehuelche and Wichi, were selected for short tandem repeat (STR) investigation. The metropolitan population of the city of Buenos Aires was analyzed, with both micro- and minisatellites. The minisatellite loci D1S7, D2S44, D4S139, D5S110, D8S358, D10S28, and D17S26 were typed on HaeIII-digested DNA obtained from unrelated individuals. D1S80 was typed by polymerase chain reaction (PCR). The autosomal STRs THO1, FABP, D6S366, CSF1PO, TPOX, F13A1, FES/FPS, vWA, MBPA/B, D16S539, D7S820, D13S317, and RENA4 and the sex chromosome STRs HPRTB, DYS385, DYS3891, DYS38911, DYS19, DYS390, DYS391, DYS392, DYS393 and YCAII were also investigated. As a by-product of our investigations, a reference database was created that is routinely used in forensic casework and paternity testing. STR allele frequency distributions are characterized by significant differences within and also between different populations. In contrast, the minisatellite bin distribution of the metropolitan population is not significantly different from other Caucasian populations.