Hemicrania continua (HC) is a headache entity completely responsive to indomethacin. Since 1984, 18 cases have been described, 15 females and 3 males, i.e. a F:M ratio of 5.0. The finding of a female preponderance, like that in chronic paroxysmal hemicrania, is a new observation. HC is, in general, a unilateral headache in the sense that it sets in on one side and subsequently sticks to this side. In two cases, both sides might possibly be involved, when the pain was at its maximum. In another (somewhat dubious) case the headache was bilateral. The pain was continuous from the beginning in 8 of 18 cases (early stage ratio continuous: non-continuous = 0.8). Over time, the headache developed a continuous character in 16 of the 18 cases, producing a "continuous: non-continuous ratio" of 8:1. The intensity of pain generally was moderate and was not reported as excruciatingly severe by any patient. The autonomic involvement from a clinical point of view, was clearly less pronounced than that of other unilateral headaches, such as cluster headache and chronic paroxysmal hemicrania.