Objectives: The aim of the current study was to evaluate the integration of mental health program into primary health care system. Method: In a cross-sectional, quantitative and qualitative study, the knowledge, attitude and performance of 1209 individuals of general population, 146 behvarzes, 35 health technicians and 51 general practitioners from rural health centers of Gilan, Tehran, Meshad, Iran, Kerman and Kermanshah universities of medical sciences who were undercoverage and out of coverage of mental health program in the rural areas of selected centers, were selected by randomized cluster sampling. The data was gathered using knowledge, attitude and performance questionnaires of behvarzes, general population and general practitioners toward mental health, behvarzes’ performance on training, following up and referral of mentally patients based on primary health care (PHC) program, knowledge and attitude of general population toward mental illnesses, epilepsy, mental retardation, their  causes and treatments, general physicians awareness about treatment, referral and integration of mental health program into PHC, general practitioners’s performance of health centers and a semi-structured questionnaire for focus group discussion sessions (FGD). Thirty trained mental health experts from neighborhood of selected provinces, completed questionnaires and analyzed. Descriptive statistics and independent t-test were executed. Results: There was significant difference between behvarzes in areas under coverage and out of coverage in knowledge (p≤0.01) and attitude (p≤0.04), as well as between general population in areas under coverage and out of coverage in knowledge (p≤0.001) and attitude (p≤0.001). Although the knowledge of general practitionners in the coverage areas were high, the findings showed that 34.3% of them had difficulty in diagnosis and 48.6% had problem in treatment of psychotic patients. Conclusion: Integration of mental health programs into PHC is an effective and affordable method which with continuous monitoring and evaluation could be lead to valuable results.