Human identification can be accomplished by several technical procedures, especially by the comparative analysis of dental documents. Recent advances in molecular biology have now widened the scope for human identification and defined the protocols for the collection of biological material. Allele patterns of a population are particularly useful and they should be verified since they vary in different populations. We have studied the frequency of the alleles in three STR loci of the Y chromosome (DYS390, DYS391 and DYS393) in a group of Brazilian caucasian subjects. Results presented alleles 21, 22, 23, 24, 25 and 26 in locus DYS390, alleles 8, 9, 10, 11 12 and 13 in STR DYS391 and alleles in STR DYS393 were 11, 12, 13 14 and 15. The highest frequencies were 24 (0.46), 11 (0.37) and 13 (0.45). Each of the three STR systems had a PE (power of exclusion) of 0.6764 (DYS390), 0.5988 (DYS391) and 0.6136 (DYS393), The combination of the three STR systems revealed a PE of 0.9498, suggesting that this data can help in human identification.