Phenol was administered to 30 male and 30 female Sprague-Dawley rats (Taconic Farms, NY) in the drinking water at concentrations of 200, 1000 and 5000 ppm; the control group was given unadulterated water. Parental (PI) rats were treated for 10 weeks prior to mating, during a two week mating period, throughout gestation, and through lactation until sacrifice. The F, generation was treated following a regimen similar to P,, while the Fz generation was not intentionally exposed to the phenol. After mating, approximately 10 P, males/group were used for evaluation of standard clinical pathology parameters and immunotoxicity screening using a plaque assay. There was no evidence of immunotoxicity, and a minimal increase in blood urea nitrogen (BUN) was noted in the 5000 ppm group. No other alterations in hematology or clinical chemistry were noted. Significant reductions in water, and to a lesser extent food consumption, were observed in the 5000 ppm group across both generations. The decreased water consumption was believed to be due to flavor aversion. Corollary reductions in body weight/body weight gain were also observed in both generations at 5000 ppm. In addition, some absolute organ weights were significantly reduced in the 5000 ppm group, while some organ-to-body weight ratios were significantly increased. In general, the alterations in organ weights and organ-to-body weight ratios observed across both generations were considered to be secondary effects of the reduced body weight.