Under the Rio Declaration and Agenda 21 from the United Nations Conference on Environment and Development in 1992 and other international agreements such as the Stockholm Convention on Persistent Organic Pollutants and the Strategic Approach on International Chemical Management, Thailand is currently in the process of adopting the Pollutant Release and Transfer Register [PRTR] through the pilot project in Rayong province with the assistance from the Japan International Cooperation Agency. This research aimed to study perceptions of private sector towards the PRTR through a case study on the petrochemical industry in the Map Ta Phut Industrial Estate. The methodology used comprised reviews concept, development and application of the PRTR, as well as the petrochemical industry in Thailand and its emission. Data collection was conducted by interviewing and questionnaire to thirty-two petrochemical companies, four responsible organizations and four key informants. Through semi-structured questionnaires and in-depth interviews towards various stakeholders including private sector, public sector and civil society, this study found that petrochemical industry in this study viewed that benefits of the PRTR for the government and civil society is quite clear, while each petrochemical company participated in this study has different understanding on such benefit for private sector to be as sustainable industrial management. Various incentive measures and concerns on the PRTR were also indicated in this study. In order to successfully implement the PRTR in Thailand, the research findings suggest that it would be important to increasing knowledge on the PRTR both public and private sectors and the risk of chemical substances, enhancing mutual understanding among stakeholders, and building the capacity of public sector to improve the PRTR process. Future research may increase the number of participants and focus on different kinds of industries or local communities. The relationships between the scale of company and needs of assistance would be also important to be studied more deeply for an effective implementation of the PRTR.