Vinyl acetate monomer (VAM) was administered in drinking water supplied ad libitum at doses of 5,000, 1,000, and 0 ppm (v/v) to 17-week-old Sprague-Dawley rats (breeders) and to 12-day embryos (offspring). Treatment lasted for 104 weeks; thereafter, animals were kept under control conditions until spontaneous death. VAM was found to cause an increase in total malignant tumors and in carcinomas and/or precursor lesions of the oral cavity, lips, tongue, esophagus, and forestomach. Based on these data, VAM must be considered a multipotent carcinogen.