Eight alleles of the STR system D3S1358 were observed and sequenced. The alleles ranged in size from 119 bp (13 repeats) to 147 bp (20 repeats) and consist of two diverse tetranucleotides: [AGAT] and [AGAC]. Alleles 16 and 17 show basic repeats which are different in one base. The allele frequency of 499 unrelated persons from SW-Germany yielded no deviation from Hardy-Weinberg equilibrium. A comparison with a Portuguese population showed some small differences, i.e. one allele has not been found in the Portuguese sample until now. The mutation rate was estimated with 0.8% analysing 65 families.