The access to antineoplastic drugs has been a major concern affecting cancer patients on treatment plan as well as treatment costs. This descriptive study aimed to assess and compare the situation of access to anticancer drugs between Thailand and benchmarked countries, and to explore determinants influencing the accessibility of antineoplastic drugs in Thailand. The data on drug registration information of antineoplastic medications approved during 1982 and April 2016 were acquired from websites of the drug regulatory agency of studied countries including Thailand, Singapore, Malaysia, US, UK, and EMA. The result showed that Thailand had registered 88 out of 180 active pharmaceutical ingredients (APIs) of antineoplastic listed by WHO, comparing with 130 APIs registered in USA, 119 in UK, 75 in EMA, 92 in Singapore, and 68 in Malaysia. Of 88 APIs registered in Thailand, 38 were listed under National List of Essential Medicine (NLEM) for patient access. The time lag, which was time difference between market authorization approval (MAA) date in Thailand and in the compared country, was reported that on average Thailand has anticancer drugs available in the market 37.26 months later than US, 4.52 months than UK, 12.22 months than EMA, 10.73 months than Singapore, and 6.51 months than Malaysia. Trend analysis illustrated that the market access of antineoplastic drugs has been improved overtime from 87.59 months during 1983-1990 to 23.62 months during 2007-2016. However, the longer waiting time for patient access was reported. It took 88.05 months on average for a product to be listed under the National List of Essential Medicine (NLEM) after registered in Thailand. The analysis on determinants of market access pointed that the only significant determinant explained market access of antineoplastic drugs was the novelty level. The API listed as the 2nd or 3rd me-too was found to enter Thai market faster than others of the same classification. The study concluded that market access of antineoplastic drugs in Thailand had been improved overtime and comparative with Singapore and Malaysia. It was recommended that the process for anticancer drugs to be listed under NLEM for broader patient access needed to be revised.