Adult chronic immune thrombocytopenic purpura (ITP) is a disorder manifested by varying degrees of purpura and mucosal bleeding, rarely including intracranial hemorrhage. Therapy is aimed at increasing the patient's platelet count to safe levels and includes a wide variety of treatments. While the diagnosis, treatment, and prognosis of chronic ITP have been extensively discussed, the effect of ITP and its treatment on patient quality of life has not been evaluated in adults. In this study, the Short-Form 36 questionnaire was used to evaluate the health-related quality of life (HRQOL) of 73 adult ITP patients compared with that of the general U.S. population and of patients with six other relatively common chronic disorders. This study shows that the HRQOL of adult patients with ITP is significantly worse than that of the general U.S. population. It is also worse than that of patients with hypertension, arthritis, or cancer; similar to that of patients with diabetes; but better than that of patients with congestive heart failure or a missing or paralyzed limb. Future studies need to address the effects of treatment not only on the platelet count and bleeding but also on HRQOL.