The majority of previous studies on unilateral headaches beyond migraine and cluster headache have focussed on certain disorders such as paroxysmal hemicrania, SUNCT and primary stabbing headache. We assessed headache characteristics, importance of neuroimaging and response to indomethacin in an unselected series of uncommon unilateral headaches. We investigated all consecutive patients presented with unilateral headaches not fulfilling ICHD-II criteria of migraine and cluster headache. Patients underwent cranial magnetic resonance imaging or computed tomography as well as an indo-test, i.e. oral indomethacin 75 mg b.i.d. for 3 days. Among 63 patients we diagnosed primary stabbing headache in 12 patients, (probable) paroxysmal hemicrania in 6 and tension-type headache in 3 patients. One patient each had probable SUNCT, new daily persistent headache and nasociliary neuralgia. Eight patients had a secondary headache and 31 could not be classified according to ICDH-II. Imaging revealed lesions causally related to the headache in 8 patients. Indo-test achieved full remission of headache in 13 of 51 patients. At follow-up 11 ± 3 months after the first visit 29% of the patients were headache-free for ≥3 months. In conclusion, almost half of the patients presented with unilateral headaches beyond migraine and cluster headache cannot be classified according to ICHD-II. Among classifiable headaches primary stabbing headache was the most common. Imaging should be considered to rule out secondary headaches. The course is favourable in one third of the patients.