Anxiety is supposed to interfere with cognitive and emotional processing and high level of trait-anxiety has been associated with an attentional bias for fearful faces, even in sub-clinical anxiety. On the basis of the Spielberger State and Trait Anxiety Inventory (STAI), twenty students were grouped as low vs. high anxious. Pictures from the Ekman and Friesen series were used in an event-related potentials study to investigate the neurophysiological correlates of the emotional processing of fear and happiness in sub-clinical anxiety. Subjects were confronted with a visual oddball design, in which they had to detect, as quickly as possible, deviant happy or fearful faces amongst a train of standard stimuli (neutral faces). Anxiety does not modify early perceptual (N100, P100, N170, VPP) or attentional (N2b) component, but later components are affected. Indeed, high anxious subjects are faster to detect deviant faces as suggested by earlier reaction times and P3b component. However, they show a reduced ability to process the emotional content of faces, this deficit being indexed by a decreased N300 component. Indeed, N300 is supposed to be particularly sensitive to affective features of stimuli rather than to physical characteristics. We propose that the earlier P3b observed in high anxious subjects could be interpreted as a way to overcome the deficient emotional appraisal by a more salient conscious processing.