A fluorescent multiplex PCR that simultaneously amplifies five X-chromosomal short tandem repeat (X-STR) loci (DXS6803, DXS981, DXS6809, DXS6789 and DXS7132)was set up to study their polymorphic nature and to determine its use in kinship tests for forensic cases. PCR products were analyzed using capillary electrophoresis and ABI prism 3100 Genetic Analyzer with GeneMapper ID 3.1 Analysis Software. The pentaplex system gave satisfactory results as its sensi-tivity, reproducibility and unambiguous genotyping. About 20 ng DNA was routinely used, although 0.25 ng DNA was suf-ficient for allele typing. The results demonstrate that the multiplex system of the five X-STR loci provides a fast technology for forensic identification and paternity testing. The X-STR pentaplex system can complement the analysis of AS-STR and Y-STR efficiently, especially in complex cases of kinship testing.