<正>Objective: To study the genetic variation of mitochondrial DNA（mtDNA） among common laboratory strains of inbred mice. Methods: The genetic polymorphism of mtDNA among 4 classical laboratory strains of inbred mice and 3 inbred strains of mice established in China was analyzed by polymerase chain reaction coupled with restriction fragment length polymorphism（PCR-RFLP） and PCR coupled with single-stranded conformation polymorphism（PCR-SSCP）. Results: With regard to the D-loop（Displacement loop

D-loop）

tRNAMet+Glu+（?）e

and ND3（NADH dehydrogenase subunit 3

ND3） gene fragments of mtDNA from these mice

no variation was revealed by PCR-RFLP at 46 restriction enzyme sites. Further analyzed by PCR-SSCP

the D-loop 5’fragment and 3’end fragment of mtDNA from these mice also showed no genetic variation. Conclusion: Owing to maternal mode of inheritance of mtDNA

the results indicate that these common inbred strains of mice share the same maternal lineage.