Cervicogenic headache (CEH) has been said to be common among patients with idiopathic headache, but no information exists as to its prevalence among those who have not suffered whiplash or head injury. This study was designed to answer this question and in addition to determine whether headache relief could be achieved by blockade of the occipital nerves (greater and lesser occipital--GON, LON) in the upper neck, on the side habitually affected by the headache. Among 796 patients with idiopathic headache, 128 or 16.1% were found to be suffering from CEH. They were predominantly female, as in the case of migraine, older than the migrainous group (49.5 years as against 34.7 years), respectively, and with a monthly headache frequency of 18, against 6.9 in the case of migraine. Injections of depot methylprednisolone into the region of the GON and LON produced complete relief of headache in 169 out of 180 patients with CEH for a period ranging from 10 to 77 days, the mean duration of relief being 23.5 days. However, similar relief of headache could be achieved in patients with attacks of strictly unilateral migraine or cluster headache, suggesting that local steroid injections by blocking the cervico-trigeminal relay, can arrest other forms of unilateral headache.