Shea oleine, an oil fraction derived from the nut of the tree Butyrospermum parkii, is used as a frying oil. As part of a series of studies, this investigation examined the carcinogenic potential of 15% (w/w) shea oleine in comparison with 15% (w/w) sheanut oil, and palm oil following dietary administration to rats over 104 weeks. The assessment comprised an evaluation of mortality, clinical signs, body weight, food intake, clinical pathology, organ weights and macroscopic and histopathological examination plus tumour type and incidence evaluation. Results showed that shea oleine produced no adverse effects and no evidence of tumorigenic potential compared to other commercially available sheanut and palm oils in the rat. Notable differences were confined to reduced body weight gain and food intake, reduced cholesterol and increased alkaline phosphatase levels, reduced heart weight and an increased incidence of pulmonary lipidosis with shea oleine diets. The latter effect may reflect a naturally lower incidence of this finding with palm oil diets. Tumour findings, specific to shea oleine diets, were restricted to an increase in the number of hepatomas for females, pancreatic exocrine adenomas for males and skin keratoacanthomas for males fed shea oleine diets. The increase in the incidence of hepatomas with treatment was thought to be related to the high fat content of the diets. The incidence of these tumour findings was similar to that given in published data for the Wistar rat, or the 'in house' values for tumour incidence in rats fed high-fat diets. In conclusion, none of the findings in this study were considered to be adverse effects. In comparison with other commercially available edible oils, shea oleine showed no tumorigenic potential following dietary administration at 7.5 g/kg/day in the rat.