The objective of this study is to assess the differences in access to antiretroviral treatment among health insurance recipients, using a patient-based analysis. METHODS: The subjects were 324 outpatients with the human immunodeficiency virus who were treated at a regional hospital for infectious diseases in Khon Kaen Province. We collected data every visit of the patients during the study period between April1 and September 30 in 2002. We defined access to antiretroviral treatment as having a prescription for antiretroviral drugs on at least one visit during the study period. We examined the relationship between access to antiretroviral treatment and age, sex, stage of acquired immune deficiency syndrome (AIDS), and health insurance. We also compared the results of the patient-based analysis and the record-based analysis that was used in our previous study. RESULTS: Multiple logistic regression analysis shows that patients insured by the Civil Servant Medical Benefit Scheme have better access to antiretroviral treatment than the others (vs. Universal Coverage; odds ratio=11.38, 95% confidence interval=4.09, 31.65). We have also shown that patients with AIDS-related complex have better access to antiretroviral treatment compared to asymptomatic AIDS patients (odds ratio=3.38, 95% confidence interval=1.31-8.76). Values of these odds ratios were lower in the record-based analysis than in the patient-based analysis. CONCLUSIONS: Patients insured by the Civil Servant Medical Benefit Scheme had better access to antiretroviral drugs. We reconfirm the differences in access to antiretroviral treatment among health insurance recipients, using the patient-based analysis.