Microplastics (MPs) are currently global environmental pollutants, and their associated health risks cannot be ignored. However, research on MP toxicity in mammals is limited. We investigated the effects of polystyrene microplastic (PS-MP) particles on the lipid profile and oxidative stress markers of Wistar rats. Two forms of PS-MP-pristine polystyrene and Styrofoam microplastics-particles of diameter <5 mm were used in this study. Each form was separately incorporated into rat feed in varying proportions of 1, 5 and 10%. A total of seventy rats (thirty-five male and thirty-five female rats) were used for this study and were separately distributed into seven groups of five rats each. The rats were then randomly assigned to a control group which received normal rat feed and water and six (6) test groups which were fed varying percentages (1, 5 and 10) of polystyrene microplastics diet for a period of 90 days. The rats were sacrificed under mild diethyl ether anesthesia 12 hr after cessation of treatment and blood was collected for lipid profile and oxidative stress analyses. Results obtained showed that oral exposure to microplastics caused decreased high density lipoprotein cholesterol (HDL-C) and increased low density lipoprotein cholesterol (LDL-C) in the rats. In contrast, there were no significant changes in oxidative stress parameters in the rats following microplastics exposure. Atherogenic indices in the PS-MP exposed rats differed according to gender. These results indicated that PS-MP dietary exposure may lead to dyslipidemia and male rats had higher cardiovascular risk.