This book constitutes the refereed proceedings of the 6th International Conference on Similarity Search and Applications, SISAP 2013, held in A Coruña, Spain, in October 2013. The 19 full papers, 6 short papers and 2 demo papers, presented were carefully reviewed and selected from 44 submissions. The papers are organized in topical sections on new scenarios and approaches; improving similarity search methods and techniques; metrics and evaluation; applications and specific domains; and implementation and engineering solutions.