The present study investigated the effects of cigarette smoking on prepulse inhibition (PPI) of the acoustic startle reflex in healthy men. Cigarette smoking in a group of overnight smoking-deprived smokers increased PPI as compared to the smoking-deprived condition. This finding is consistent with previous animal studies showing that nicotine increases PPI of the acoustic startle reflex. In addition, cigarette smoking also reduced startle amplitude during the first 6-7 min of the post-smoking session.