A population study was carried out on a random sample of 164 individuals from North Portugal using the short tandem repeat (STR) system hTPO (locus: 2p23-2pter). After electrophoresis, 7 alleles were identified of which 6 had been previously described and a new one, estimated to be 134 bp long. The observed genotype distribution is in Hardy-Weinberg equilibrium. In order to assess the forensic applicability of the system, namely for paternity investigations, 109 mother-child pairs were analysed. No exclusions were found and the observed distribution did not deviate from the expected. Since hTPO has a relatively high information content (PIC = 0.60; H = 0.65) this system can be very useful in paternity investigations.