Ten X-chromosome short tandem repeats (X-STRs: DXS8378, DXS7132, DXS9898, DXS6809, DXS6789, DXS101, GATA172D05, HPRTB, DXS8377, and DXS7423) were analyzed in a sample of unrelated individuals (108 males and 110 females) from the Santander Department in Colombia. In this sample, gene diversities varied between 63.56%, for DXS8378, and 91.41%, for DXS8377. For this set of 10 X-STRs, a high discrimination power was obtained for both male (1 in 3 x 10(6)) and female (1 in 9 x 10(10)) samples and a high mean exclusion chance in father/daughter duos (99.993%) and in father/mother/daughter trios (99.9999%), demonstrating the usefulness of this set of markers in forensic and kinship analysis. Hardy-Weinberg equilibrium was tested in the female sample and no significant deviations were found. Pairwise analysis showed significant differences in the comparison with samples from Spain, Peru, and Argentina and with African American and Hispanic samples from New York. This same set of X-STRs was also typed in 51 mother/father/daughter trios, 43 mother/son duos, and in a single father/daughter pair. In total, four mutations were observed; one at DXS7132 and at DXS6809, and two at DXS8377. Two mutations were paternal and one maternal; and to a fourth mutation, it was not possible to define its origin.