In the period 1987-2011, 387 cases of occupational asthma (OA) in local workers (LL) and 32 in migrants (LM) were diagnosed in the 36 level Center of Occupational Medicine at University of Padova. Total number of OA decreased from early nineties to 2011. However the proportion of OA in migrants increased from 0.7% to 36.4% along the study period. Severity and causing agents were similar in the two groups. The most frequent cause were isocyanates (68.7% LM vs 52.7% LL). Most of OA in migrants was observed in painters (46.9%), whereas the jobs in asthmatic LL were more widely distributed.