A variable region of the 28S ribosomal RNA gene was amplified with primers that are complementary to flanking sequences phylogenetically well conserved. The products of 12 animal DNA's (human, Japanese monkey, dog, cattle, pig, cat, rabbit, mouse, rat, chicken, frog, and fish) were separated by polyacrylamide gel electrophoresis; each revealed a few bands that ranged from 150 to 100 base pairs. The band patterns obtained from each DNA sample differed in number and size which indicates the applicability of the method to species identification. Samples that contained either as little as 1 pg of DNA or degraded DNA of 0.2 to 0.5 kb in length were able to provide detectable bands. Postmortem human tissue DNA's were tested as an example. They showed a pattern identical to the human control one, which was distinct from those of the other animals examined. The study thus concludes that rDNA typing that uses ribosomal gene primers is useful for species identification in human and animal tissue DNA's. 5 figures and 14 references (Author abstract modified)