In the second semester of 1999, 246 patients, living in a Roman urban area, were subjected to a prick-test screening. 194 (78.9%) of the patients showed a positive answer toward almost one of the tested allergens, whereas the other 51 persons (21.1%) turned out to be negative. Of the patients with a positive cutireaction, 59 (24% of total survey and 30.4% of allergic subjects), with an average age of 29.6 (SD = 12.78) showed sensitization toward cypressus. The results were compared with a case-study of 900 atopic subjects, recruited by the same Center between 1994-96 and living in the same Roman area. In this last group we only found 84 pts (9.3%) with a positive prick-test toward Cypressus, with an average age of 35.2 (DS = 13.48). This analysis wants to stress the increasing incidence of allergy toward cypressus among atopic subjects, switching from 9.3% to 30.4%, in the same urban area, during these last three years.