Chronic daily headache (CDH) represents a group of non-paroxysmal headache disorders that occur on a daily or near-daily basis, for longer than 6 months. Even though it is a common problem, affecting 30-70% of the patients attending specialized headache clinics, it is not a well-defined and classified disorder, resulting in controversies regarding its description and approach. The aim of this study was to evaluate the clinical presentation of CDH due to transformed migraine and possibly compare the differences among male and female patients. Two hundred and seventy-one patients, 217 women and 54 men, ages 16-83 (mean 37.5 years for women and 41.4 for men), fulfilling the proposed criteria for transformed migraine and selected from a group of 300 consecutive CDH patients attending a subspecialty headache centre, were studied retrospectively. The most observed clinical presentation was pressure or tightening, bilateral fronto-temporal, moderate non-continuous headache, with a progressive onset. The association with nausea and phonophobia was demonstrated in 60% and 32% of the patients, respectively. The association with photophobia (29.6% male, 44.2% female, P = 0.05) sleep (77.7% male, 49.8% female, P = 0.0002) and emotional (87% male, 64.1% female, P = 0.001) disturbances, as well as the occurrence of intermittent full-blown migraine attacks (81.5% male, 95.4% female, P = 0.001) was significantly different among male and female patients. Overuse of symptomatic medications (SM) was observed in 87% of the male and in 83.8% of the female patients, with a significant difference concerning the use of more than one type of SM (male 68% compared with female 91.7%; P = 0.006). We concluded that TM patients have a clinical presentation compatible with previous descriptions but suggesting, even though limited by the restricted number of male patients, different aspects among male and female patients.