The ability to recognize familiar and unfamiliar individuals is important as it plays a central role in many social interactions. Previous research has found that some animal species can discriminate among conspecifics, and recent findings indicate that some species are also able to discriminate among heterospecifics, including humans. The ability to discriminate between humans based on voice recognition has been thoroughly investigated in domestic species and in some wild species housed in captivity. However, human voice recognition remains largely untested in wild animals living in their natural environment. In the present study, we investigated whether wild Western Australian magpies can discriminate between the voices of familiar and unfamiliar humans using playback experiments. Magpies showed an increase in vigilance when exposed to playback of unfamiliar voices compared with familiar, suggesting that magpies perceive unfamiliar humans as a greater threat. These results provide the first evidence that birds in their natural environment have the capacity to discriminate between humans using vocal recognition. Given that humans can represent a threat for wild animals, this capacity to discriminate based on vocal familiarity may be beneficial.