The action of the specific inhibitor of fatty acid synthesis cerulenin has been studied in excised roots of 5-6-day-old wheat seedlings grown in CaCl2 solution (2.5 x 10(-4) mol/l). Cerulenin decreases heat production and oxygen consumption. Cerulenin also increases plasma membrane permeability for ions and stops adaptive processes of roots. The decrease of heat production and oxygen consumption by roots is probably caused by reduced energy expenditure on fatty acids and lipid biosynthesis and ion-transporting systems.