To date, only a single proven case of autochthonous human alveolar echinococcosis has been recorded in Minnesota in 1977. At that time, echinococcal lesions removed from the patient were experimentally inoculated into voles, and the parasite materials obtained from the voles were preserved as histopathologic specimens for 30 years. In this study, retrospective genetic analysis of larval Echinococcus multilocularis originating in the human case was performed using the histopathologic specimens. DNA was extracted from the hematoxylin and eosin-stained specimens, and mitochondrial cytochrome c oxidase subunit 1 gene (cox1) was amplified by polymerase chain reaction. Subsequently, 20 small fragments (100-216 bp) covering almost the entire sequences (97%) of the cox1 were successfully amplified, and the nucleotide sequence analysis showed that the E. multilocularis isolate from Minnesota was almost identical to an isolate from South Dakota rather than isolates from contiguous Alaska.