We studied the occurrence of threat display as a defensive behavior at different temperatures in two large-sized (Gallotia simonyi and Gallotia stehlini) and two small-sized (Gallotia atlantica and Gallotia caesaris) lacertids from the Canary Islands. Lizards were chased on a linear track at five temperatures (24, 28, 32, 36, and 40 C). Only adult individuals of the two large-sized species sporadically adopted the threat display, and G. stehlini used the display more often than did G. simonyi. Among these, there was no clear pattern of relationship between temperature and probability of display nor differences between sexes.