Although Lew/Crl rats are central to a classic model of renal transplantation and may provide a valid system for evaluating the effect of obesity on transplantation outcomes, their response to high-fat diet has not been evaluated sufficiently. The objective of this study was to evaluate biometric and basic metabolic data of Lew/Crl rats fed a 60% kcal, lard-based, very high-fat diet (HFD) compared with those fed a 10% kcal fat control diet (CD). Rats were maintained for 17 wk; body parameters and caloric intake were monitored weekly. Biometric data were collected and calculated before and after euthanasia. Serum was evaluated for liver enzyme activity and total bilirubin, glucose, triglyceride, cholesterol, insulin, leptin, and creatinine concentrations, and urine was evaluated for protein, glucose, specific gravity, and ketones. Tissues were harvested, weighed, and evaluated histologically. Compared with CD rats, HFD rats consumed more calories and weighed more after 3 wk. After 17 wk, HFD rats had significantly increased body weight, girth, volume, epididymal fat pad weight, omental weight, and body fat. In addition, HFD rats had mild elevations in some liver enzymes and a lower serum triglyceride concentration than did CD rats. Histologic assessment and other metabolic markers of disease were not different between the 2 groups. Lew/Crl rats fed a 60% kcal HFD become obese, but they lack significant metabolic abnormalities frequently associated with obesity in other rat strains.