Therapeutic effectiveness of lithium carbonate in cluster headache is confirmed on the ground of the results in 20 patients (14 with the episodic form, 6 with the chronic one). Outstanding findings were: a) the early effectiveness; b) the occurrence of therapeutic effects even with low doses; c) the negligible risk of side effects. The way interrupting the treatment in episodic cluster headache is proposed. In chronic cluster headache recurrence can be expected when lithium is stopped, but in some cases it occurs after a long free interval. The contrast is stressed between the high efficacy in all the 20 patients with cluster headache and the complete uneffectiveness in 5 patients affected by headaches considered as borderline between cluster headache and migraine.