[en] The objectives of the study are to conceive the data based on the utilization of radiation and radioisotopes in Thailand and the inventory of radioactive waste arising from such utilization. The suggestions of the future radioactive waste management are also given as well. Data collection was done by mean of questionnaire and interviewing 245 radioisotope users in Thailand. The outcome can be summarized as follows:. Increase in the quantity of radioisotope in all sectors of the utilization was found, especially on the applications in nuclear medicine and industry. The amount of radioactive waste is increasing accordingly. The waste from unsealed radioisotopes increase 10.68 percent per year for liquid wastes and about 6.39 percent per year for solid waste. Most of these wastes are subjected to transfer for treatment by the Office of Atomic Energy for Peace (OAEP). The wastes from sealed radiation sources were packed in shielded containers. Most of these wastes would be shipped to the country of supply, but, some will be handled by OAEP. The accumulated wastes volume after treatment and conditioning, in the next 30 year will be around 220 cubic meter, excluding the wastes from the operation of nuclear research reactor, nuclear power plant, decommissioning, used sealed sources and the wastes from mining and milling of radioactive ores