The present study was undertaken to investigate the application of M13 bacteriophage as a probe for DNA fingerprinting in domestic animals. l. Hypervariable polymorphic patterns were detected with M13 phage DNA as a probe in genomic DNA of chickens and pigs digested with restriction enzymes. Hinf I was the most useful restriction enzyme for generating the informative DNA fingerprints. 2. Individual-specific restriction patterns were generally observed from all three different animal species in this study. However the individuals in the particular breed of chicken showed much more similar Southern blotting patterns compared to those from the different breeds. 3. The protocols were modified for generating more well resolved and wide spectrum of hypervariable bands. The principal differences between our protocol and those of others: a change of restriction enzyme, longer gels, very long gel runs with continuous change of electrophoresis buffer. 4. The data obtained also demonstrate a potential range of M13 DNA applications as a probe for DNA fingerprinting in domestic animals, particularly for the determination of species, identification of inbred lines, and the development and fixation of the useful breeds.