Allele distributions of 10 short tandem repeat (STR) polymorphic DNA loci used in forensic and paternity testing were determined for a cohort comprising 163 individuals representing a mixed Jewish Caucasian population. Typing was carried out by the commercial AmpF lSTR SGM Plus kit. The polymorphism and the utility of three of these markers for forensic studies in Israel were established for the first time. Results were compared with data for U.S. Caucasians and African Americans. The probability of identity of two persons of different ethnic origins for identification purposes is discussed. A lemma is presented to show that the chance of erroneous identification of an innocent person who belongs to a population that had not committed a crime will, in most cases, be smaller than for those who belong to a population that had truly committed the crime.