Previous studies have provided electrophysiological evidence for attentional abnormalities in patients with post-traumatic stress disorder (PTSD). The present study examined the electrophysiological activity of trauma-exposed patients with or without a PTSD during a modified Stroop task. The PTSD group showed a reduced P2 and P3 amplitude relative to the non-PTSD group under both the earthquake-related and earthquake-unrelated words conditions. Importantly, the earthquake-related words elicited a greater P3 amplitude (350–450 ms after stimulus) than did unrelated words in the non-PTSD group, whereas no significant difference was found in the PTSD group. This indicates that PTSD patients had some attention deficits compared with non-PTSD individuals, and that these attention deficits were not just limited to earthquake-related words.