Y chromosome haplotype data was collected for 155 Irish males residing in the Republic of Ireland. Eleven short tandem repeat (STR) markers: DYS19, DYS385, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438 and DYS439 were analysed and the allele and haplotype frequencies calculated. This Irish data is presented here and was found to be less diverse when compared with the neighbouring UK population.