Using the Minnesota Multiphasic Personality Inventory and the Millon Clinical Multiaxial Inventory, we assessed the psychological functioning of U.S. Air Force veterans exposed to Agent Orange and its contaminant, 2,3,7,8-tetrachlodibenzo-p-dioxin (dioxin), during the Vietnam War. Index subjects were veterans of Operation Ranch Hand (N = 1,109). Comparisons (N = 1,493) were U.S. Air Force veterans not involved with spraying herbicides. We found few consistent psychological abnormalities associated with serum dioxin levels. Ranch Hand veterans with higher dioxin levels showed some difficulties in anxiety, somatization, depression, and a denial of psychological factors. However, those with background levels also showed indications of emotional distress, primarily in emotional numbing and lability; a guarded, suspicious, and withdrawn style of relating to others; and unusual thoughts or behaviors.