Allele and genotype frequencies for three short tandem repeat loci were determined in a population sample from Catalonia (NE Spain). After denaturing PAGE electrophoresis, 11 alleles were identified for D12S391 (n = 167), 9 alleles for CSF1pO (n = 282) and 6 alleles for TPOX (n = 283). No deviation from Hardy-Weinberg equilibrium was found. The allele frequencies observed are similar to those of other compared European populations.