Abstract Behavioural thermoregulatory temperature preference was investigated prior to and following both mild (approximately 10 °C) and deep (0 °C for 1 hr) hypothermia. Temperature preference of adult male hamsters (Mesocricetus auratus) was assessed with apparatus specifically designed and constructed for that purpose. Each of the ten sets of apparatus consisted of five individual boxes arranged as a pentagon around a central arena. The temperatures of the boxes were controlled so that a subject could select environmental temperatures of 1 °, 6 °, 12 °, 18 ° or 26 °C. Activity was continuously monitored on an event recorder which was controlled by photocells at the entry ways of each box. Box temperature was monitored with recording thermocouples. All animals lived in the apparatus from 4 to 35 days before the initial hypothermia. Eight hours prior to hypothermia the mean time spent per hour in the 26 °C box was 5·38 min, with the remaining 6·2 min per hr being divided approximately equally between the other four boxes. Upon regaining normal body temperature following hypothermia the animals were returned to the chambers. Immediately after being returned, the hamsters exhibited a preference for the 6 °, 12 ° and 18 °C environments. The duration of this post-hypothermic temperature preference was significantly longer following mild hypothermia than that following deep hypothermia. Following this ‘down-shift’ all animals returned to the 26 °C box where they stayed for an average of 56·6 min per hr over a period of at least 8 hr. Consistent with the impaired thermoregulatory stability and the labile body temperature generally observed following hypothermia, one might expect these animals preferentially to select the warmest environmental temperature (26 °C). However, the post-hypothermic, transient, ‘down-shift’ to the lower environmental temperatures might suggest that as a result of some physiological readjustment (vasomotor activity, metabolism, hypothalamic ‘set’) during this period that the thermocomfort ‘set’ of these hamsters has also been temporarily altered.