Nineteen Y-specific short tandem repeat (STR) loci have been amplified in 768 samples from the Iberian Peninsula in order to evaluate their usefulness in forensic casework. Two previously published multiplex reactions by Thomas et al. [Hum. Genet. 6 (1999) 577] (MS1, modified here: DYS19, DYS388, DYS390, DYS391, DYS392 and DYS393) and by Ayub et al. [Nucl. Acids Res. 28 (2000) e8] (CTS: DYS434, DYS435, DYS436, DYS437, DYS438 and DYS439) plus a novel one reported here (EBF: DYS385, DYS389, DYS460, DYS461, DYS462 and amelogenin) have been used. DYS385, DYS439 and DYS391 were the most informative loci with allele diversities of 0.7997, 0.6683 and 0.5940, respectively. A total of 635 different haplotypes were observed, of which 573 (90.24%) were found in single individuals. The overall haplotype diversity was 0.9988 and that obtained by each multiplex system was 0.9812 for EBF, 0.9292 for MS1 and 0.9089 for CTS.