Forty-six farmers were patch tested to determine whether their dermatitis was secondary to an occupational allergen. Twenty-eight had a positive patch test of which 23 were thought relevant (definite or probable). In 20 of these cases, the allergen(s) was considered to be work related (define or probable). The common allergens were pesticides (N-(1,1,2,2-tetrachloroethylthio) -4-cyclohexene-1,2-dicarboximide (captafol), ethylenebis (dithiocarbamato) manganese (maneb) and copper sulfate), rubber compounds (N-isopropyl-N-phenyl-4-phenylenediamine (IPPD) and 4-phenylene diamine base) and sunscreen chemicals.