The aim was first to examine the differential effects of crude and refined palm oil (CPO and RPO) on the lipid and lipoprotein constants of plasma in rats and to compare the effect of crude palm oil to that of fish oil. Secondarily, it was to know whether one can take advantage from the association of CPO with FO. Twenty-four-day-old weaning rats were divided into five experimental groups, each receiving a purified diet containing 10% oil as either a single oil or an equal amount of two oils. After a feeding period of 36 days, the main results were as follows. As compared to the rats fed the RPO diet, those fed the CPO diet had lower total cholesterol, LDL-C, VLDL-C and apoB and higher HDL-C/LDL-C and apoA1/apoB ratios. Those fed the FO diet had only lower VLDL-C and triglycerides and higher HDL-C and HDL-C/LDL-C ratio. Whereas FO associated with RPO in the same diet had the same effect as FO alone, FO associated with CPO tends to reinforce the effect of CPO. This is particularly true for the effects on apoB and apoA1 which were found to be synergistically depressed and enhanced, respectively. Given the role played by these biological constants as predictors of CVD in humans, and in spite of the fact that these predictors are not relevant in rats, these results would suggest the potential interest of CPO or the association of CPO with FO in human nutrition.