Hospitals in Thailand operate in a multiple insurance payment environment. This paper examines (1) access to medicines and other medical technologies, (2) treatment outcomes, and (3) efficiency in resource use, among beneficiaries of the three government health insurance schemes in Thailand. Using 2003-2005 outpatient and inpatient data for patients with three tracer diseases from three government hospitals, we find that utilization of more expensive items differs between patients whose insurers pay on a closed- or open-ended basis. Where new vs. conventional drugs are both available, patients whose insurer pays on a fee-for-service basis tend to have greater access to new drugs, compared to patients whose insurer pays on a capitated or case basis. Similar patterns were found where there are options between originator versus generic drugs, drugs in different dosage forms, and more versus less advanced diagnostic technologies. Effects of insurance payment are more pronounced where price gaps among the medical technologies are significant. Efficiency results are mixed, depending on nature of the disease conditions and type of resources required for treatment.