Introduction: Morning headache (MH) is often a symptom associated with obstructive sleep apnea syndrome (OSAS). There are also patients with MH but without OSAS. What is the importace of MH in the management of patients with OSAS and vice versa? Materials and methods: We reviewed scientific articles in various medical journals (Cephalalgia, Slee Med, Springer Science, Arch Intern Med, Acta Neurol Scand, Tex Med, Arch Neurol, etc.) until 2014. Results: The prevalence of MH in the general population is 5-7%, in patients with OSAS 11-74%. According to the literature, there are two types of MH: associated with OSAS and not associated with OSAS, the latter being included in The International Classification of Headache Disorders, 3rd edition (beta version). The principally criterion for establishing of the MH associated with OSAS is it resolution after OSAS treatment. MH that is not associated with OSAS is attributed to other forms of primary headache. It is possible that MH to be generated by both: OSAS and primary headache. Conclusions: A detailed description of MH is important for excluding primary headache in the OSAS patients management. For the patients with MH, it is important to perform cardiorespiratory polygraphy to exclude OSA