The aim of the present study is to identify and prioritize the most important five occupational risk factors perceived by representatives of workers in each one of the economical activity branches (EAB) in Barcelona, by the Delphi Method. A Delphi survey was carried out for each EAB of Barcelona. 273 trade union delegates (from 21 to 28 by EAB) were consulted the three successive postal interviews. The typical risk factors (noise, toxics, and infections agents) appeared in the first and second place in the printing, food, textile, chemical and health branches of activity. However, risk factors related to work organization were pointed out in the first place in the rest of branches. The use of the Delphi method by the occupational health managers of a geographical area could let, in an easy and fast way, identify and prioritize the risk factors of this area in order to introduce effectiveness prevention measures.