Fifteen male users of oral snuff participated in an experiment where we used an auditory-visual vigilance task to study nicotine effects on P300 and response parameters. Quantitative EEG was also studied. Fifteen male nonusers served as controls. We found some decrease of response times and a tendency towards improved signal detection. P300 parameters were not affected in this study. Quantitative EEG analysis indicated an expected increase of arousal, as the activity within the alpha band shifted towards higher frequencies.