Lizards from different families use acoustic signals in different communicative contexts. This study characterizes the hissing sounds emitted by individuals of Pristidactylus volcanensis (Polychrotidae) of both sexes, when confronted with a threatening stimulus. These hissing sounds have broadband spectra centered at 2.4–3.6 kHz throughout most of the emission. In some cases the hisses end with a downward frequency modulation component within the frequency range of the ongoing signal. The structure of these sounds resembles the alarm signals produced by other vertebrates in response to extremely stressful situations, such as an imminent predator attack. The occurrence of sound production in other Polychrotidae suggests that these displays have an ancestral origin in the family; however, the scattered occurrence of acoustic signals in lizards, points to an independent evolution of sound production in different families of these reptiles.