Latent inhibition is a slowing of learning about a stimulus that when previously experienced had no consequences. This study investigated the effects of tobacco smoking and personality traits on a latent inhibition task. Two-hundred and five healthy adults performed an auditory masking task during which half of them were pre-exposed to bursts of white noise. All subjects were then asked to detect an association of the white noise with a change on a computer screen. Subjects who had heard the white noises before were slower to learn the association than subjects who had not, i.e. they showed latent inhibition. Latent inhibition was stronger when subjects were pre-exposed to 10 rather than 6 bursts of white noise. Latent inhibition was reduced in subjects who smoked tobacco and in non-smoking subjects who scored highly on a schizotypy questionnaire. These two effects were independent. We conclude that tobacco smoking should be taken into account in interpreting the results of human latent inhibition studies.