Background: Depression is a mood disorder that results in negative thoughts, disruption of thinking, sleep and appetite. A depressive disorder is occurring with cognitive impairment, and depressed patients tend to suffer decreased performance. The study aims to assess the incidence of depressive disorder and its association with functional disability and cognitive impairment. Determine the impact of a depressive disorder associated with cognitive impairment on functional disability among patients. Methods: This study is descriptive cross-sectional which included 150 patients from Makkah and treated at King Abdulaziz Hospital. Results: The mean age of patients in this study was 36.12±10.93, the male and female were in equal ratio 1:1. The most prevalent degree of depression was severe depression 31.3%, followed by mild depression 29.3%, no depression 20.7% and finally moderate depression 18.7%. Age, sex, education, and occupation significantly affected the severity of depression. There was a positive correlation between cognitive dysfunction and functional disability (P-value=0.001, r=0.433), with a strong positive correlation to family life (P-value=0.001, r=0.71). Conclusion: Severe depression was the most prevalent degree of depression, and it was significantly associated with cognitive impairment, functional disability and decreased work productivity. The increase in the severity of depression was related to the greater cognitive impairment and increase in functional disability as well as work productivity. Functional disability increases with increasing in cognition dysfunction.