Fifty-three patients with chronic fatigue syndrome (CFS) and 43 healthy nonpatient controls completed the Minnesota Multiphasic Personality Inventory (MMPI). All subjects varied in their degree of seropositivity to active Epstein-Barr virus (EBV) as measured by their anti-early antigen titers. EBV titers were higher among CFS patients and were associated with being more symptomatic. Differences in patient status were associated with statistically significant elevations on 8 of 9 clinical scales, 4 of which also showed clinically significant elevations (T scores > or = 70): scales 1, 2, 3, and 8. These results are discussed in terms of their implications for intervention strategies associated with MMPI-based CFS subtypes.