Catecholaminergic function was studied in rat brain areas after acute administration of S-adenosyl-L-methionine (SAM: 10 mg/kg i.p.). The noradrenaline (NA) concentration increased in the hippocampus and frontal cortex and decreased in the olfactory bulbs between 1 and 2 h after the SAM injection. NA biosynthesis was stimulated in vivo and the concentration of normetanephrine was increased only in the hippocampus. SAM may indirectly affect NA biosynthesis and metabolism. This effect on noradrenergic function might participate in its putative antidepressive action.