The aim of this research was to investigate the effects of supplementing two products, soybean oil (SBO; 0.2kg/d) or SBO+citrus pulp (CPP; 1.0kg/d), at two different sites, rumen or abomasum, on intake, total tract apparent digestibility (TTAD) and ruminal fermentation. Four ruminally fistulated lactating Holstein cows were assigned to a 4×4 Latin square design with a 2×2 factorial arrangement of treatments: 1) SBO administered in the rumen; 2) SBO infused in the abomasum; 3) SBO+CPP administered in the rumen; and 4) SBO+CPP infused in the abomasum. Basal DM intake was lower for cows fed SBO+CPP than for those fed SBO only (16.5 versus 17.3kg/d) and infusion in the abomasum tended (P=0.07) to decrease it compared to administration in the rumen (16.6 versus 17.1kg/d). Ruminal pH and ammonia N concentration were similar among treatments. There was an interaction between product and site of supplementation for total volatile fatty acids concentration as administration of SBO+CPP in the rumen increased it compared to that of SBO and infusion of the products in the abomasum had no effect. There was a trend (P=0.09) for lower TTAD of crude protein with administration of products in the rumen compared to infusion in the abomasum and supplementation with SBO+CPP compared to SBO led to higher TTAD of ether extract. Treatments had no effect on TTAD of dry matter and neutral detergent fiber. Ruminal or post-ruminal supplementation of soybean oil with citrus pulp compared with that of soybean oil had little effects on TTAD of nutrients and ruminal fermentation characteristics. There was no advantage for a source of antioxidants such as citrus pulp to bypass the rumen when cows were supplemented with polyunsaturated fatty acids as SBO.