Correct material identification is considered essential when documenting museum objects. This study examines the morphology of mammal hair and records the geographical use of common species in Inuit fur clothing collected by the National Museum of Denmark (NMD) from c. 1830–1940 in the Bering Strait region, Alaska, Arctic Canada, and Greenland. Through hair microscopy, the purpose is to test whether original identifications are correct to assess the origin of unique Inuit garments. By means of transmitted light microscopy (TLM) of stained, 1 µm thick cross-sectioned hairs and undyed, longitudinally mounted hairs, the research reveals that specific morphological structures are characteristic of the common native reindeer/caribou, musk ox, members of the seal family, domestic dog, wolf, Arctic fox, polar bear, and wolverine. Rarer animals (hare, lynx, otter, etc.) are not part of this study because of limitations in the collection. Hairs from seal species are difficult to distinguish from one another. Hairs from dog and wolf are distinguishable but have relatively similar morphology. Therefore, to confirm identification, supplementary analyses are required. The hair microscopy technique was used on 49 garments in NMD’s collections, and the results were compared to the original macroscopic species identification. The study revealed that the latter method is often erroneous when it comes to dog/wolf and wolverine fur.