The aim of this study was to analyse the distribution of Y-chromosomal haplotypes and haplogroups found in central Portugal. In this work, we analysed 102 unrelated individuals of central Portugal. Combining the allelic state of 10 biallelic markers (YAP, SRY-8299, 92R7, 12f2, SRY1532, SRY-2627, Tat, SY81, M9, LLY22g), we defined the haplogroup to which each sample belonged. Y-chromosomal haplotypes were defined by 16 Y-Short Tandem Repeats (STR) (DYS19, DYS385 a/b, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS460, DYS461, GATA A 10, GATA C4 and GATA 114). This population study defined 8 different haplogroups and 101 different haplotypes, where 100 haplotypes were unique and 1 was found in two apparently unrelated individuals, both belonging to the same haplogroup. (C) 2003 Elsevier B.V. All rights reserved.