Five hundred subjects were patch-tested on the one hand with 25 allergens standard group and on the other hand with selected allergens depending on the occupation and history of each patient. They systematic standard series are responsible for 79 p. 100 of contact allergens. Among them the most frequent sensitizers observed include potassium dichromate, nickel sulfate, cobalt chloride, paraphenylenediamine, propylene-glycol, triethanolamine, balsam of Peru. The selected allergens stand for 21 p. 100 of our cases. These results are compared with those of other countries. The main sensitizers are involved in every case. However a few discrepancies are to be noted: turpentine and mercury do not occupy with us a foremost rank, whereas prophylene-glycol and triethanolamine which, according to our statistics, stand fourth and seventh, are not mentioned elsewhere. Differents factors can partly account for these variations: industrial products are submitted to local influence, as it occurs with turpentine for instance, environmental factors play an important part too and, above all, local industries. Nevertheless, this study brings into relief two facts:--the interesting use of systematic standard series, constantly updated, since they are responsible for 79 p. 100 of contact allergens;--the incidence of each patient's history and occupation on the choice of selected allergens, thanks to which we can put into relief less usual causes, though they should not been overlooked, since they stand for 21 p. 100 of the allergens so far listed.