This study conducted a cost-utility analysis and a budget impact analysis (BIA) of outpatient oral chemotherapy versus inpatient intravenous chemotherapy for stage III colorectal cancer (CRC) in Thailand. A Markov model was constructed to estimate the lifetime cost and health outcomes based on a societal perspective. Eight chemotherapy strategies were compared. Clinical and cost data on adjuvant chemotherapy were collected from the medical records of 1747 patients at Siriraj Hospital, Thailand. The cost-effectiveness results were interpreted against a Thai willingness-to-pay threshold of USD 5003/quality-adjusted life year (QALY) gained. A 5-year BIA was performed. Of the eight strategies, CAPOX then FOLFIRI yielded the highest life-year and QALY gains. Its total lifetime cost was also the highest. An incremental cost-effectiveness ratio of CAPOX then FOLFIRI compared to 5FU/LV then FOLFOX, a commonly used regimen USD was 4258 per QALY gained.The BIA showed that when generic drug prices were applied, 5-FU/LV then FOLFOX had the smallest budgetary impact (USD 9.1 million). CAPOX then FOLFIRI required an approximately three times higher budgetary level (USD 25.1 million). CAPOX then FOLFIRI is the best option. It is cost-effective compared with 5-FU/LV then FOLFOX. However, policymakers should consider the relatively high budgetary burden of the CAPOX then FOLFIRI regimen.