Objective.—To determine whether there are any differences in health-related quality of life between patients with migraine and those with transformed migraine. Background.—There are no published reports comparing the health-related quality of life between patients with migraine and patients with transformed migraine. Methods.—We conducted a retrospective analysis examining the health-related quality of life of patients with transformed migraine and migraine seen at a specialty headache clinic. Data collected included the Short Form-36 (SF-36) and the Migraine Disability Assessment questionnaires as well as demographic information. Both of these forms are part of the initial evaluation at the headache clinic. A t test with Bonferroni correction was used to test for significant differences in the SF-36 domains between the groups. Results.—Data were collected for 90 patients, 46 with transformed migraine and 44 with migraine. There were no significant differences between groups with respect to sex, race, or age. Over the last 90 days prior to their first visit, patients with transformed migraine reported having a headache an average of 69 days compared with patients with migraine who averaged 18 days with headache (P<.05). Compared with patients with migraine, patients with transformed migraine had statistically (P<.05) and clinically significant (difference >5 points) lower mean scores on seven of the eight SF-36 domains and both the mental and physical summary scores of the SF-36. Conclusions.—The results of this study suggest that patients with transformed migraine have a lower health-related quality of life than patients with migraine. These findings indicate that the headache chronicity associated with transformed migraine has a significant influence on quality of life. The results highlight the importance of effective management of headaches to avoid the progression of migraine to the more disabling transformed migraine.