In vitro amplification of the alphoid repeated sequences clustered in the centromeric regions of the human X and Y chromosomes was carried out. A modification of the amplification conditions reported by Witt and Erickson gave clear amplification bands from 10 pg of genomic DNA template. Results were obtained from the following aged tissue samples: 1 microL three-year-old blood stain, one-year-old single hair roots, six-month-old saliva stains and twelve-year-old bone fragments. Good results were obtained even when the template was artificially fragmented into fragments of less than 1 kbp.