Background: Headache disorders are most prevalent public-health problem. Worldwide, among the adults 46% suffer from primary headache, where the migraine presents 11% and tension type headache (TTH) presents 25%. Recently, one type of the primary headache, medication overuse headache tends to increase. Nowadays, there is no sufficient study about primary headache in Mongolia. So that, it is necessary to investigate prevalence, clinical type and risk factors of the primary headache. Purpose: To study prevalence and risk factors of primary headache in Mongolia. Materials and Methods: This cross-sectional study was carried out from June to November of 2017. Participants aged 18-65 years old were randomly selected from four provinces and three districts of Ulaanbaatar city. The diagnosis of headache was made using the International Classification of Headache Disorders-3 beta. Statistical analysis was performed on SPSS-23 program. Results: A total of 2043 participants (812 men and 1231 women) were reviewed. The participant’s average age was 38.6±13.4years. 1350 (66.1%) participants reported recurrent headache within the last 1 year. Of the total study population, the prevalence rate of primary headache was 1305 (63.9%). Number of people who suffered from migraine was 494 (24.2%), significantly greater in female than male participants (p=0.0001), with most frequent attacks at age 26-45 years. The risk of migraine associated with sex, education and family history (p=0.001). 592 (29.0%) of participants had TTH, mean age of them was 37.7±5.24, significant high rate in female than men, risk of TTH depends on education and job. The medication overuse headache was diagnosed at 116 (5.7%), 29.4% in men and 70.5% in women with average of 45.6±11.4 and 43±12.7 respectively. Among the participants 38.6% used medications, 28% people had one drug, 8.5% two drugs and 2% used three or more drugs. Use of non-steroid anti-inflammatory drugs (NSAID) made up major percent in headache patients. Increased frequency of medication and multidrug affected to medication overuse headache (p=0.008). Conclusion More than half of studied population had primary headache. Migraine was in 24.2%, TTH in 29.0% of people, and associated with sex, education and family history. Use of non-steroid anti-inflammatory drugs made up major percent in headache patients.