The effects of an antimetabolite, 6-aminonicotinamide (6-AU) on the levels of glucose, glycogen, catechoamines and mucleotides in mice brain were investigated. The level of glucose in the blood starts increasing from 3 h after administration of 6-AU while those in the brain tissue start increasing from 9 h after administration of 6-AN. The concentration of brain glvcogen remained unchanged at all time points except 11h. The level of epinephrine in the brain was found to reach maximum value at initial 3 h following 6-AU administration, after urhich it started dec$ulcorner$easing si역서cantle. The Brvel of brain norepinephrine remained virtually unchanged before 24 h time point at which it starts decreasing significantly. ATP, CTP, UMP and UTP levels were significantly reduced but AMP and CMP levels urere not affected.