Using an attentional blink paradigm, we show that the typical enhancement of perception for emotionally arousing events is significantly reduced in Asperger's syndrome (AS) at short inter-target intervals. Control experiments demonstrate that this finding cannot be attributed to differences in the perceived arousal of the stimuli, or to a global impairment affecting any type of modulation of perceptual encoding. Because a functioning amygdala is critical for emotional modulation of the attentional blink, the findings support a role for the amygdala in the pathophysiology of AS. More specifically, they suggest there is a fundamental failure of the amygdala to modulate processing in cortex, a concept at the heart of some recent theories of amygdala involvement in the aetiology of autistic-spectrum disorders.