The purpose of this study is to report allele frequency data of three ethnic Amerindian population samples: the Otomi (Hna-hnu) from eastern Sierra Madre and Ixmiquilpan valley and the Huasteco from La Huasteca. These groups were characterised by 15 STR-PCR polymorphisms (HumTH01, HumvWA, D18S51, HumTPOX, D19S433, D16S539, D13S317, D8S1179, D7S820, D5S818, HumFGA, CSF1PO, D2S1338, D3S1358 and D21S11). No significant deviations in observed allelic frequencies from Hardy-Weinberg equilibrium were found for all the studied systems. From the forensic point of view, the heterozygosity value, power of discrimination and the a priori chance of exclusion were calculated