Objective: To determine the cost of treatment for schizophrenic patients in Social Security scheme, Thailand. Methods: The paper reviewed available evidence in Thailand on the cost of schizophrenia treatment in different hospital settings and data of health service utilization obtained from various sources. The sensitivity analysis of direct health care cost of schizophrenia was conducted in social security system, both in outpatient and inpatient services. The cost for schizophrenia coverage per individual social security applicant was estimated in different contexts. Results: The total cost of treatment depends on the service utilization rate and unit cost of treatment. The annual direct health care cost of schizophrenic outpatients in Thai social security scheme was averagely estimated at about 171 million Baht. (Range: 28.5 million to 372 million Baht in sensitivity analysis). The annual direct health care cost of schizophrenic inpatients in Thai social security scheme was averagely estimated about 265.3 million Baht (Range; 22.7 million to 531 million Baht in sensitivity analysis). Aggregation the outpatient and inpatient treatment for schizophrenic employees accounted for 436.5 million Baht/year (Range from 436.5 million to 903 million Baht). The cost for schizophrenia coverage per individual social security applicant was about 48 Baht/year. (Range 5.63 Baht to 99.22 Baht). Conclusion: This study illustrated the cost of schizophrenia treatment in Thai social security scheme in various contexts, which might be useful in planning, preparing, budgeting and decision making. However, the huge societal impacts of schizophrenia should be carefully considered for policy makers.