Guinea pigs were exposed to 1,1,2-trichloroethane applied directly on the skin of the back for periods between 15 minutes and twelve hours under anaesthesia. Morphological changes could be observed in the epidermis after 15 minutes and continued to progress during continuing exposure. The changes consisted of pyknotic nuclei, perinuclear oedema of basal and suprabasilar cells as well as a focal separation of the epidermis from the corium with vesicle formations. The liver tissue showed reduction of glycogen content as well as hydropic changes in the centrilobular areas six hours after the start of exposure. The liver changes were less marked 12 hours after exposure and absent in nonanaesthetized animals. No morphological changes were observed in the kidney or the brain.