To investigate whether the processing of faces and emotional facial expression can be modulated by spatial attention, ERPs were recorded in response to stimulus arrays containing two faces and two non-face stimuli (houses). In separate trials, attention was focused on the face pair or on the house pair, and facial expression was either fearful or neutral. When faces were attended, a greater frontal positivity in response to arrays containing fearful faces was obtained, starting about 100 ms after stimulus onset. In contrast, with faces located outside the attentional focus, this emotional expression effect was completely eliminated. This differential result demonstrates for the first time a strong attentional gating of brain processes involved in the analysis of emotional facial expression. It is argued that while an initial detection of emotionally relevant events mediated by the amygdala may occur pre-attentively, subsequent stages of emotional processing require focal spatial attention. The face-sensitive N170 component was unaffected by emotional facial expression, but N170 amplitudes were enhanced when faces were attended, suggesting that spatial attention can modulate the structural encoding of faces.