The presence of epoxy resin in a reformulated immersion oil for microscopy has caused an epidemic of occupational contact dermatitis in laboratory technicians from some European centers. We report 6 additional cases, the mode of presentation of which was similar to the European patients. All patients were patch tested to the undiluted oil, and some were tested to the European or North American standard series and to an extensive series of glues and adhesives allergens. At 96 hours, all 6 patients displayed a strong 2+ to 3+ reaction to the undiluted oil. Two patients were not further tested, but in the remaining 4, positive reactions were seen to epoxy resin from the standard tray. One patient reacted to cycloaliphatic epoxy resin, and 2 displayed positive tests to the reactive diluents phenyl glycidyl ether and cresyl glycidyl ether. These further cases confirm the strong sensitizing properties of this particular immersion oil. The product, manufactured by Leica Microsystems (Wetzlar, Germany), since has been withdrawn from sale.