Background: Mental health patients with self-stigma often loss their self-esteem. The objectives: This study was conducted to determine the prevalence rate of mental illnesses stigma and its association with quality of life in adult Saudi patients attending the out patient's in psychiatry department in King Fahad University Hospital at Al Khobar, KSA. Methods: This is a cross sectional study. A demographic data including age, sex, marital status and occupation were collected in addition to a 32 question-based questionnaire with different variables divided into three parts; To gain further perspective on discrimination experienced by persons with mental illness. To study rejection experienced by mentally ill patients. To evaluate the patients coping ways to stigma which characterized by secrecy, avoidance and withdrawal, and advocacy and confrontation. Results: There were 71 (34.6%) women, 112 (54.6%) men. About third (36.6%) of respondent agrees that people think of mentally ill patients as untrustworthy. Almost half of them (44.9%) disagree that people find them dangerous. The same percent (44.9%) agree that people take them less seriously.41.5% of them feel that people avoid them. More than half of them 51.2% disagree that someone will not take them as close friend. But 54.6% didn't feel any avoidance from relative, neighbors or colleagues (missing data 11.2%). 67.8% also, didn't feel any avoidance from family members. More than half (55.1 %) tries to hide the fact that they are mentally ill and 72.2% will not avoid getting married or starting a family because of their mental illness history. Conclusion: Our study indicated that most of mental health patients in our community have experienced moderate to severe level of stigma. Future researches are needed to study the prevalence of stigma and rejection in mental health patients allover Saudi Arabia. Community awareness campaigns to raise the knowledge that mental illness is a disease like other body diseases and there is no shame of being mental health patient.