Chronic daily headache (CDH) represents a group of any headache disorder that occurs on a daily or near daily basis, for longer than 6 months. Even though it is a common problem, it is not a well defined disorder, resulting in controversies regarding its identification, description and approach. Three hundred patients, 232 women and 68 men, ages 16 to 86 (mean 38 years old for the women and 42 for the men), attending a headache center and fulfilling the proposed criteria for CDH (Silberstein et al.) and presenting headache 28 days per month were retrospectively studied. The clinical features allowed the primary headache diagnosis, before the transformation into daily presentation as: transformed migraine (TM ) in 271 patients (90,3%), chronic tension-type headache (CTTH) in 26 patients (8,7%) and new daily persistent headache (NDPH) in 3 patients (1%). Among the TM patients, the most observed 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 and sleep disturbances, as well as the occurrence of intermittent headache attacks, was different among male and female patients. With regard to the CTTH patients, pressure or tightening, bilateral fronto-temporal, moderate non-continuous headache, with sleep disturbances and no associated symptoms, was the predominant presentation.