Psychological trauma is associated with poor physical health. We examined whether specific trauma types (assaultive, sexual, any) are associated with specific medical illnesses and whether posttraumatic stress disorder (PTSD) mediated these relationships in 680 primary care patients. For men, trauma history was associated with arthritis and diabetes; PTSD mediated the association between trauma and arthritis but not diabetes. Among women, trauma was associated with digestive diseases and cancer; PTSD did not mediate these relationships. Awareness of the presence of the physical illnesses examined here may help with the identification and treatment of primary care patients with trauma histories.