The recent technology of amplification of DNA sequences by the polymerase chain reaction (PCR) has already proved to be a very useful tool for the analysis of variable number of tandem repeat (VNTR) loci. Short tandem repeat (STR) loci appear as other promising PCR-based identification systems. In fact, DNA typing based on PCR amplification of STRs is very sensitive and allows to overcome major problems encountered when using the RFLP method, such as typing of very small amounts of DNA, highly degraded DNA or mixtures of DNA from more than one individual. Two STR systems, HUMTH01 (a tetranucleotide repeat (AATG) sequence located on chromosome 11) and HUMFES/FPS (a tetranucleotide repeat (ATTT) sequence located on chromosome 15) were investigated in order to determine allele and genotype frequencies for a French caucasian population sample. HUMTH01 and HUMFES/FPS alleles were amplified by the use of PCR and amplified STR sequences were analyzed on 6% Hydrolink Long Ranger gels and visualized by silver staining. The study was conducted on a sample of unrelated individuals (N approximately 190) randomly selected from the French caucasian population. The genotype distributions met Hardy-Weinberg expectations for both HUMTH01 and HUMFES/FPS STR systems. Furthermore, an additional allele, never reported before was observed at the HUMFES/FPS locus: it migrates as an allele containing 7 repeat units and corresponds to the smallest allele identified for this locus.