Abstract: A method of discriminating individual organisms which comprises conducting a polymerase chain reaction using DNA fragments of test individuals and a primer having a symmetrical base sequence, separating the amplified DNA fragments by polyacrylamide gel electrophoresis, staining each of the separated DNA fragments by silver staining, and comparing the stained DNA fragments with each other; the above method of discrimination wherein the primer having a symmetrical base sequence is one member selected among the following ones: 5'-CCCTAAAGAAATCCC-3', 5'-TTTAGGGCGGGATTT-3', 5'-AGGGCCTTCCGGGA-3'; and the above method of discrimination wherein the individual organisms are animal or plant individuals. The method of the invention enables individual discrimination to be performed efficiently on the basis of a difference in DNA sequence, because it is possible to clearly ascertain different DNA fragments exhibiting polymorphism among test individuals.