The forensic value of Y-STR markers in Guiné-Bissau was accessed by typing of 215 males. Allele and haplotype frequencies, determined for loci DYS19, DYS389-I, DYS389-II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439 and the duplicated locus DYS385, are within the limits of variation found in other populations south of the Sahara. The level of discrimination achieved is Guineans is higher than for European or other African populations with comparable data. The haplotype diversity of 0.9995 is reduced to 0.9981 when the minimal haplotype is considered thus revealing the importance of increasing the number of typed loci.