The prefrontal cortex (PFC), especially the medial sector, plays a crucial role in emotional processing. Damage to this region results in impaired processing of emotional information, perhaps attributable to an inability to initiate and maintain attention toward emotional materials, a process that is normally automatic. Childhood onset damage to the PFC impairs emotional processing more than adult-onset PFC damage. The aim of this work was to study the involvement of the PFC in attention to emotional stimuli, and to explore how age at lesion onset affects this involvement. To address these issues, we studied both the emotional and attentional modulation of the startle reflex. Our sample was composed of 4 patients with childhood-onset PFC damage, 6 patients with adult-onset PFC damage, and 10 healthy comparison participants. Subjects viewed 54 affective pictures; acoustic startle probes were presented at 300 ms after picture onset in 18 pictures (as an index of attentional modulation) and at 3,800 ms after picture onset in 18 pictures (as an index of emotional modulation). Childhood-onset PFC patients did not show attentional or emotional modulation of the response, in contrast to adult-onset PFC damage and comparison participants. Early onset damage to the PFC results, therefore, in more severe dysfunction in the processing of affective stimuli than adult-onset PFC damage, perhaps reflecting limited plasticity in the neural systems that support these processes.