One of today's most decorative and popular ornamental potted plants is Croton. Handling this plant over a period of 6 months produced contact eczema of the hands in a nursery gardener. Patch tests with Croton leaves were positive. Control tests remained negative. Sensitization experiments in guinea pigs with a methanolic extract of the leaves were successful. All results of the study indicate that: -latex of croton produces no primary irritant reaction -latex is able to induce a real contact allergy -contact allergens are constituents of the milky sap. Whether the di- and triesters of phorbol so far isolated as irritant and cocarcinogenic factors from the latex of various Euphorbiaceae species and sensitizers shall be investigated in further experiments.