The HUMARA CAG repeats polymorphism was studied in an Italian population sample. Polymerase chain reaction amplification and automated fluorescent analysis were used. A total of 19 and 15 repeats was observed in female and male subjects, respectively, and one new allele was found. The authors conclude that this X-linked short tandem repeat, typed without ambiguity and with a heterozygosity of 0.902, is useful in parentage testing of female subjects.