Average age for all subjects was 53 (SD=5.9) years. Average years of education for the sample was 11.7 (SD=2.6) years. Average total CAPS-2 score for the group was 97.3 (SD=17.9), average CAPS-2 subscale scores were as follows: CAPS-2 reexperiencing-24.3 (SD=7.4) CAPS-2 avoidance-40.1 (SD=8.7), CAPS-2 arousal-32.7 (SD=5.2). Distribution of the APOE genotype was as follows: 2/2—16.7%, 2/3—3.7%, 2/4—5.6%, 3/3—44.4%, 3/4—29.4%, 4/4—0%. In addition to meeting criteria for PTSD, 81.5% of the sample met SCID lifetime or current criteria for either major depression or dysthymic disorder, 18.5% of the sample met criteria for panic disorder, 64.8% met criteria for lifetime alcohol abuse or dependence, and 13% met criteria for lifetime substance abuse or dependence. Due to the relatively small number of subjects, we initially tested our hypothesis by comparing subjects with one APOE4 allele (2/4, 3/4) to all other subjects. No significant differences in PTSD symptoms or memory were noted between groups. However, when a comparison was made between subjects with at least one APOE2 allele (2/2, 2/3, 2/4; N=14) and the remainder of the sample (N=40), those subjects with the APOE2 allele had significantly higher CAPS-2 reexperiencing scores (29.7 , compared to 22.4 ; t=3.49, p=0.001, two-tailed t test) than the remainder of the study sample, but did not differ from the remainder of the sample in terms of avoidance or arousal symptom clusters. When comparisons were made between groups given neuropsychological testing (N=33), those subjects with at least one APOE2 allele (N=9) performed significantly poorer on several of the WMS-III’s Immediate Memory scales (Logical Memory (LM): (5.5 [SD=1.1] compared to 9.5 [SD=2.9]; t=−3.69, p<0.001; Family Pictures [FP]: 6.82, SD=2.41 compared to 9.71, SD=2.22; t=−2.93, p=0.007) than the remainder of the sample, but did not differ on any of the WCST measures. In the subject sample with at least one APOE2 allele, more elevated CAPS-2 reexperiencing symptoms correlated significantly with lower FP scores (r=−0.859, p=0.013), though not with lower LM scores.