Saturated fatty acid (FA) supplements are commonly based on palmitic acid (PA), stearic acid (SA), and oleic acid (OA). Commercial fat supplements reacted with magnesium oxide have also become available. Recent work has indicated that abomasal infusions of OA and chemical emulsifiers increase FA digestibility. Lecithin is a natural emulsifier, but its effect on fat supplements has not been well investigated. Our hypothesis was that the inclusion of OA and lecithin in a FA supplement would increase FA digestibility and milk production without decreasing intake. Treatments were included at 1.75% of the diet and were prills made from a base free FA mixture containing 33.6% PA, 59.4% SA, and 2.9% OA (SF; used as a control), or prills made from the base with 1.9% added OA (SFO), the base FA blended with 10% soybean lecithin (SFOL), the base reacted with 4% magnesium oxide (MS) or the base reacted with magnesium oxide with 2.4% added OA (MSO). Ten multiparious (151 ± 45 DIM) and 5 primiparous (113 ± 23 DIM) Holstein dairy cows were arranged in a 5x5 Latin square design with 14-d periods. Digestibility was calculated using 240 h iNDF with acetone rinse. The statistical model included random effects of cow and period, the fixed effects of treatment and parity, and the interaction of treatment and parity. There were no differences between treatments for DMI (22.3 ± 0.3 kg), milk yield (37.7 ± 0.4 kg), or milk fat and protein concentration or yield (P > 0.10). Dry matter and NDF digestibility were also not affected. The MSO, SFOL, and SFO treatments increased total FA digestibility 1.5, 1.3, and 1.0 percentage units compared with MS, respectively. C16 FA digestibility was increased 6.8 and 5.9 percentage units by SFOL and MSO compared with SF, and was also increased 10.4, 9.5, and 7.3 percentage units by SFOL, MSO, and SFO compared with MS, respectively (P < 0.001). Digestibility of 18 carbon FA was not affected by treatment (P = 0.13). Addition of OA and lecithin increased FA supplement digestibility with no effect on intake.