A total of 90 alleles found in white Caucasians from North-West Germany were sequenced and 26 alleles chosen to construct a uniform and reliable allelic ladder for the STR system ACTBP2 (SE33). In addition 3 new aspects concerning the sequence structure were observed. Population studies were carried out on white Caucasians (n = 278) from North-West Germany using the new improved ladder. A total of 24 alleles and 14 "interalleles" were found and reproducible results obtained. No significant deviation from Hardy-Weinberg-equilibrium could be observed.