Background: Provider-initiated HIV counseling and testing (PIHIVCT) is an important intervention that improves the access to care to HIV-infected patients and subsequently contributes to the success of national HIV/AIDS control efforts. However, in Thailand, the cost-effectiveness of this program is unknown.Objective: Determine the incremental cost-effectiveness ratios (ICER) in terms of Thai Baht per Quality Adjusted Life Year (QALY) of PIHIVCT for outpatient department (OPD) patients in community hospitals of Thailand compared with the current practice.Methods: A model-based health economic evaluation study was conducted based on results from cluster randomized controlled trials in 16 community hospitals of Thailand. The Markov model and the probabilistic sensitivity analysis were used. One-thousand two-hundred seventy-seven HIV-infected patients completed questionnaires on their household expenditure and quality of life using the visual analog scale.Results: In social perspectives, the PIHIVCT program increased a patient’s life span by 5.18 days or 4.15 qualityadjusted days per OPD case and the ICER was 63,588 Baht per QALY gained. The subgroup analysis showed that the PIHIVCT program would be cost-effective for cases younger than 50 years if the ceiling threshold of willing to pay equaled the per capita Gross Domestic Product (GDP). However, this intervention would be cost-effective for all cases of 13-64 year old if the ceiling threshold equaled three times of GDP.Conclusion: The provider-initiated HIV counseling and testing program for OPD patients is more cost-effective than the current practice and should be implemented in health care setting in Thailand.