Four cases of cutaneous rash, clinically more or less similar to erythema multiforme have been observed in patient who either stayed in a room with an accidentally high content of fluorocarbons, or had a skin contact with butane or phenyl-azo-beta-naphthol. The cutaneous lesions appear to be secondary to absorption of the toxic product, and probably induced by inhalation rather than by percutaneous penetration. Arguments for the responsibility of the substances rely on anamnestic data.