Headache can be classified into 14 groups according to the International Classification of Headache Disorders of the International Headache Society (IHS). Migraine and tension-type headache constitute 92% of all headaches. Lifetime incidence of headache is around 80%. It is extremely important to exclude underlying pathology as a cause of headache. The criteria of the IHS classification provide a useful framework for diagnosis. The use of questionnaires can be helpful. The first assessment of head pain can be time-consuming, and might need to be performed repeatedly. Headache diaries should be used for observation of disease progression. This is especially helpful for evaluation of therapy outcome, as well as for audit and quality control.