Background: In most health care systems, primary care doctors are the cornerstone of recognition, diagnosis, treatment, and specialist referral for all types of disorders, whether they are somatic, psychological, or both. The past two decades have witnessed a further emphasis of this role, particularly with regard to the treatment of mental disorders in primary care.⁽¹⁾ Aim of the study: to describe demograghic characteristic of the study population and determine the prevalence of mental disorder among population attending primary health care centers of Left Primary Health District in Mosul City. Materials and Methods: A biometric descriptive study was conducted in order to achieve the aim of the present study in which the data was taken from the records present in statistical, integrated management of mental unit in left primary health care district which responsible for all primary health care and family medicine centers in left side of Mosul city. Results: This study revealed that the highest frequency of mental disorder was found in the age group 20-49 years [male 2607 (21.88 %), female3793 (31.84 %], while the lowest frequency of mental disorder was observed in the age group less than 5 years [male 97(0.81%),female 66(0.55%). mental disorder are more frequently seen among female than male (56.5 % & 43.5 % respectively). the highest frequency of mental disorder is anxiety with total number in all age groups are ( 6848 ) with highest frequency in age group 20-49 years old. Conclusions: the highest prevalence of mental disorder is anxiety (6.3 in 1000 of population) and the prevalence of mental disorders in left side district in Mosul city is (10.8817 in 1000 of population).