DNA was isolated from 20 ABO-known peripheral blood samples, blood stains, saliva stains, hair, bone, and vaginal swab. Positions of nucleotide 258 and 700 of cDNA from A transferase were used to distinguish A, B, and O alleles by restriction enzyme digestion. ABO genotypes were easily determined by examining DNA fragment digestion patterns. Results obtained using this method on 20 ABO-known peripheral blood samples showed that the technique provided accurate ABO genotype. Positions of nucleotide 258 and 700 were enough to determine ABO polymorphism. Several advantages of using the method are noted: ABO genotype can be determined; the genomic DNA typing method provides definite results; in rape cases, the approach can definitely determine the rapist's blood group; and the method is simple, fast, economic, sensitive, and reliable. 22 references, 2 tables, and 3 figures