This book constitutes the refereed proceedings of the Pacific Asia Workshop on Intelligence and Security Informatics, PAISI 2015, held in Ho Chi Minh City, Vietnam, in May 2015 in conjunction with PAKDD 2015, the 19th Pacific-Asia Conference on Knowledge Discovery and Data Mining. The 8 revised full papers presented were carefully reviewed and selected from numerous submissions. Topics of the workshop are information sharing and big data analytics, infrastructure protection and emergency responses, cybercrime and terrorism informatics and analytics, as well as enterprise risk management, IS security, and social media analytics. The papers present a significant view on regional data sets and case studies, including online social media and multimedia, fraud deception, and text mining.