Starvation at an ambient temperature (Ta) of 35 °C for 72 h or at Ta 20 °C for 48 h affected differently the free fatty acid (FFA), phospholipid and glyceride pools as well as the total flux of fatty acid (msf) between the intracellular and extracellular lipid compartments of brown (BAT) and white adipose tissues (WAT). Tracer kinetic studies with 20.106 cpm/100 g body weight 14C-1-palmitic acid injected at Ta 35 °C showed that BAT takes up a consistently higher proportion of the initial serum FFA pool (ms) than WAT in both fed (group I) and fasting newborn rabbits (group II at Ta 20 °C; group III at Ta 35 °C. BAT of animals starved in the cold prior to the tracer’s injection (group II) shared a considerably larger fraction of ms than that of fed littermates (group I). Fasting in a thermoneutral environment (Ta 35 °C) consistently resulted in a very low absolute (msf) and relative (percentual msf) flow rates of FFA into BAT. In starving rabbits msF and percentual msF in WAT were consistently lower than in well-fed animals and were even more markedly reduced in animals previously starved in the cold (Ta 20 °C) than in a thermoneutral environment (Ta 35 °C).