Background: Mental disorders are more common in developed world than in developing world. Community, attitude and beliefs play a role in determining behavior of seeking help and successful treatment of patient with mental disorder. It is worth noting that ignorance and stigma prevent the mentally disordered patient from seeking appropriate help. The study aimed to investigate knowledge and attitudes of public toward mental disorders in outpatient clinics at Assiut university general hospital. This study was conducted in outpatient clinics at Assiut university general hospitals. Descriptive study was performed and multi stage sample (first, clinic choose by Random and second, patient's relatives choose by Convenience sampling was used for sex month. The total sample of this study was 1000 person from those attending to outpatient clinics with their relative patients, aged from 18 or more. The present study shows that the majority (84.7% and 83.9%) respectively of the studied sample had unsatisfactory total knowledge scores, and negative attitudes about mental disorders. Also, there is a highly statistical significant difference between total knowledge scores and age, residence, education level and occupation of study participants with P=0.000. Also, between total attitudes level, residence and educational level (P= 0.000 as well as between attitudes toward mental disorders and family history of mental disorders (P= 0.000). The study recommended that we must increase awareness and improve public's knowledge and attitude towards mental disorders through, health education for public in every health care setting that provides care for mentally disordered patients.