The DYS390 tetrameric locus is one of the most polymorphic Y-chromosome loci identified up to now. The aim of this work was to examine allele frequencies in a population sample of 128 unrelated men living in northern Poland. In the analysed population the presence of 7 alleles (out of 9 described so far) was observed. The most frequent alleles of the DYS390 locus are DYS390*25 and DYS390*24 with frequencies of 40% and 25% respectively. The values of the gene diversity and the polymorphic information content calculated for the DYS390 locus make it a useful tool for identification tests in the field of haemogenetics.