Length variation at the short tandem repeat (STR) locus HUMTH01 can be reliably detected from small amounts of DNA (0.01-10 ng) extracted from a range of forensic human samples, using the polymerase chain reaction (PCR), horizontal polyacrylamide gels and silver staining. It was shown that the oligonucleotide primers used are specific to humans and some higher primates. Population data bases of Caucasians and Asians living in Victoria (Australia) were constructed and the differences in allele frequencies between Caucasians and Asians confirmed. A new allele provisionally designated HUMTH01*12 was identified. The discrimination power provided by this locus (0.86-0.91) has been used effectively in a range of forensic case studies.