We have described respiratory allergy to the pollens of mimosa (Acacia floribunda) in some Mediterranean areas of Italy and France. The incidence of sensitivity is only 1.2% in a population of atopics but 31% in an "at risk" population of floriculturists. It seems, therefore, that the pollen of Acacia floribunda, although heavy and amphiphilous, is potentially allergenic for subjects who are in close proximity.