The STR loci HUMTH01, HUMTPOX, HUMCSF1PO, HUMF13A01, HUMFES/FPS and HUMVWFA31 are widely used in forensic casework analyses and population data are necessary to estimate the frequency of a DNA profile. This paper presents the results of a survey aimed to investigate the allele frequency distribution of these loci in an important Spanish population (Aragon, North Spain). Statistical analysis to determine whether allele frequencies were in Hardy–Weinberg Equilibrium was carried out and also to obtain some parameters of medico-legal interest. There was no evidence of association between the alleles of the loci. The Aragonese sample does not differ substantially from other Caucasian populations.