This study assesses the prevalence of specific traumatic stressors that meet criterion A for the Diagnostic and Statistical Manual of Mental Disorders' (DSM-IV) diagnosis of posttraumatic stress disorder (PTSD) and symptoms of PTSD in a representative sample of HIV-infected women. The study also assesses the impact of these stressors and symptoms on the clinical progression of HIV infection. The Life Stressor Checklist and the Impact of Events Scale-Revised were administered via interview to 67 Africa-American women beyond the initial stages of HIV infection. The ratio of CD4 t-cells to CD8 t-cells were abstracted from medical records at dates that approximated psychological interviews and were examined at two points in time 12 to 14 months apart. The prevalence of traumatic stressors and PTSD symptoms were high among HIV-infected women. Traumatic stressors were significantly associated with a lower CD4 to CD8 ratio at the 1-year follow-up. Among women who reported a traumatic event, those who also met criteria for PTSD evidenced a lower CD4 to CD8 ratio at the follow-up assessment. The study concludes that prevention and treatment efforts targeted at HIV-infected women must take into account traumatic stressors and PTSD symptoms and their potential impact on the course of the disease.