The temperature preference responses of five species of troglobite crustaceans were studied in a 15°-30°C gradient. Stygonectes hadenoecus, S. russelli and Asellus reddelli had no discernible temperature preferenda. Speocirolana bolivari had a weak preference for 20-30°C. Cirolanides texensis had a pronounced preference for 20-30°C, temperatures much warmer than that of its habitat. The lack of temperature preferenda in three species agrees with the hypothesis that imprisoned troglobites tend to lose responses to those environmental variables which are constant in caves. S. bolivari may retain its temperature selectivity because of a slow rate of cave-adaptation. It is hypothised that C. texensis is recently descended from a tropical, epigean, freshwater ancestor.