Accurate, in vivo measurements of sap flow are of increasing interest in fundamental research on plant hydraulic functioning, in assessing the effect of global climate change on forest ecosystem functioning and in optimising water management in commercial forestry and fruit cultivation. The 9th International Workshop on Sap Flow is, in 2013, the forum for international exchange of new scientific ideas and discoveries related to sap flow. All contributions will have a link to sap flow, but will go beyond sap flow discussions only. The focus will be on disseminating the latest research and innovative activities within the field of plant hydraulic functioning, including drought stress, cavitation and modelling. In addition, the workshop aims at reflecting on the hydraulic link between xylem and phloem flow. Submissions related to these topics are welcomed from different research fields (individual plants, natural and man-made ecosystems) to stimulate cross-fertilisation amongst them. Many experienced and young researchers, and R&D staff from industries, from around the world will attend the 9th International Workshop on Sap Flow. It is a unique opportunity for exchange of scientific knowledge, planning of joint research and other co-operative actions. The scientific program will include invited keynote presentations by outstanding international experts, short lectures and poster presentations. The social program should make delegates’ stay even more enjoyable.