This book constitutes the proceedings of the 8th International Conference on Similarity Search and Applications, SISAP 2015, held in Glasgow, UK, in October 2015. The 19 full papers, 12 short and 9 demo and poster papers presented in this volume were carefully reviewed and selected from 68 submissions. They are organized in topical sections named: improving similarity search methods and techniques; metrics and evaluation; applications and specific domains; implementation and engineering solutions; posters; demo papers. .