Before starting a smoking cessation treatment, 51 smokers took part in a study aimed at investigating brain mechanisms associated with attention allocation. Event-related potentials to acoustic startle probes were recorded from 129 sensors during the presentation of neutral, pleasant, unpleasant, and cigarette-related pictures. Results indicated that the amplitude of the startle probe P3 component was reduced for pleasant, unpleasant, and cigarette-related conditions relative to neutral. Surface Laplacian estimates showed that sources of electrocortical activity under frontal and parietal sensors contributed to the modulation of this effect. For smokers, cigarette-related stimuli, like intrinsically motivating ones, capture attentional resources and therefore reduce the ability to process competing stimuli. The depletion of attentional resources in the presence of cigarette-related cues may contribute to the high relapse rate observed during attempts to quit smoking.