Abstract: The effect of raw and processed Castor Bean Cake (CBC) and varying inclusion levels of Castor Bean Oil (CO) on performance and nutrient digestibility was evaluated in two trials involving albino rats. The first trial assessed the tolerance of albino rats to raw and lye treated CBC while trial II examined the growth response and nutrient digestibility of albino rats to varying levels of CO (0, 2.5, 5.0, 7.5 and 10.0%) in a completely randomized design. Twenty four weaned albino rats of average initial weight of about 28.18 g were used for each trial. In trial I, there was sharp decline (p<0.5) in feed intake, weight gain and efficiency of feed conversion as CBC increased. About 2.5 and 5% raw CBC was lethargic to rat but tolerated up to 10% lye treated CBC. Lye treatment reduced the active toxin in castor, lectin (ricin) by 55%. In trial II, feed intake, body weight gained feed conversion efficiency declined with increasing levels of CO in the diets and was significantly (p<0.05) depressed at 7.5%. Although, addition of castor oil to rat diet did not have damaging effect on performance and nutrient digestibility in this study, it will be safe not to exceed 7.5% inclusion of castor in diet of albino rat and that the seed should be properly deoiled before being used in animal feed. Lye treatment was potent in deactivating the toxic principle of CBC however, such product should not be applied in rat diet at concentration beyond 100 g kg-1 diet.