Fifty-six multiparous cows were used in a randomized complete block design to determine the effects of altering the ratio of dietary palmitic and oleic acids on production and metabolic responses. The treatments fed from 1 to 24 DIM were a control diet (CON; non-FA supplemented diet) and diets supplemented at 1.5% DM with FA supplements differing in the ratio of palmitic (C16:0) and oleic (C18:1) acids. FA treatment diets were 80:10 (80% C16:0+10% C18:1); 70:20 (70% C16:0+20% C18:1); and 60:30 (60% C16:0+30% C18:1). From d 25 to 60 postpartum (carryover period), all cows were offered a common diet to evaluate carryover effects. The statistical model included the random effect of block and cow, and the fixed effect of treatment, time, and its interaction. Results are presented in the following sequence: CON, 80:10, 70:20, and 60:30. During the fresh period, FA-supplemented diets increased milk yield (46.5, 48.6, 48.8 and 49.7 kg/d; P < 0.05), ECM (50.2, 54.8, 53.5 and 54.3 kg/d; P < 0.01), and milk fat yield (1.90, 2.15, 2.08 and 2.09 kg/d; P < 0.01) compared with CON. Increasing C18:1 in FA treatments decreased plasma NEFA (0.72, 0.84, 0.75, and 0.67 mEq/L; quadratic, P < 0.05) and BW loss (−1.55, −2.54, −1.63, and −1.48 kg/d; quadratic, P < 0.05), and tended to increase DMI (20.3, 20.7, 20.9, 21.8 kg/d; linear, P < 0.1) and plasma insulin (0.26, 0.27, 0.31, and 0.31 ug/L; quadratic, P < 0.1). Increasing C18:1 in FA treatments did not affect milk yield, ECM, and the yields of milk fat and protein. During the carryover period, cows that received FA-supplemented diets during the fresh period increased ECM (55.6, 59.5, 58.7, and 60.3 kg/d; P < 0.05), and milk fat yield (1.91, 2.06, 2.11, and 2.13 kg/d; P < 0.05) compared with CON. Our results indicate that feeding FA supplements containing C16:0 and C18:1 during the immediate postpartum period increased milk yield and ECM compared with a nonfat control diet. Increasing C18:1 in the FA supplement reduced BW loss and plasma NEFA and tended to increase DMI. Also, the diets fed during the immediate postpartum period had a tremendous carryover effect during early lactation, when cows were fed a common diet.