Studies of reactions of Namib ectotherms to potential pyrogens are important for several reasons. One is that some Namib species have selected body temperatures in the mammalian range, higher than most ectothermic species. Another is that the Namib Desert provides a suitable environment for studying endemic ectotherms in their natural habitat. The tenebrionid beetle Onymacris plana selected warmer than normal substrate temperatures, in a thermal gradient chamber, following administration of large doses of the endotoxin of gram-negative bacteria. However, the endemic lizard species Aporosaura anchietae and Angolosaurus skoogi showed no thermoregulatory responses to potential pyrogens. Future studies on the survival value of fever should include analysis of non-thermal as well as the traditional thermal components, which may have evolved separately. Also, studies are required of naturally-infected animals in their natural habitats.