Flaxseed meal (FM) is the richest source of secoisolariciresinol diglucoside (SDG), which is converted by microbes to enterolactone (EL), a metabolite with potential human health benefits. Flaxseed oil and sucrose may favor ruminal microbes involved in SDG metabolism. The objective of this study was to evaluate the effects of feeding sucrose and flaxseed oil on production and milk EL concentration in diets containing FM. Sixteen multiparous Holstein cows (94 ± 37.6 DIM and 680 ± 79.1 kg of BW) were assigned to treatment sequences in a replicated 4 × 4 Latin square with 18 d for diet adaptation and 7 d for data and sample collection. Diets were fed as TMR and included (DM basis): (1) 8% soybean meal + 23% ground corn (-control, -CRTL); (2) 15% FM + 10.7% ground corn + 5% sucrose (SUCR); (3) 15% FM + 15.4% ground corn + 3% flaxseed oil (FXO); (4) 15% FM + 10.2% ground corn + 5% sucrose + 3% flaxseed oil (SUCR+FXO). All diets contained 40% corn silage and 20% grass-legume haylage, had similar energy and RDP/RUP content and averaged 17.2% CP and 32.1% NDF. Cows fed diets containing FM had lower DMI (22.7 kg/d) than those fed the –CRTL diet (24.6 kg/d; P < 0.001). Within the FM diets, FXO and SUCR+FO had the lowest DMI (22.3 kg/d). Milk yield was greatest in cows fed –CRTL (36.2 kg/d) and lowest in those fed SUCR+FXO (33.4 kg/d; P = 0.05). Cows fed FXO and SUCR+FXO had lower ECM (31 kg/d) than those fed -CRTL (36.3 kg/d) and SUCR (36.4 kg/d; P < 0.001). Milk concentration of EL was lowest in cows fed -CRTL (76.8 nM), but no difference was observed in diets containing FM [293, 332, and 338 nM with feeding SUCR, FXO and SUCR+FXO, respectively (P < 0.01)]. Milk fat concentration and yield were lowest in diets with flaxseed oil and averaged: 3.66% and 1.33 kg/d; 3.69% and 1.32 kg/d; 2.96% and 1.03 kg/d; and 2.83% and 0.93 kg/d in cows fed -CRTL, SUCR, FXO, and SUCR+FXO, respectively (P < 0.001). Milk protein concentration and yield did not differ and averaged 2.95% and 1.01 kg/d, respectively. In conclusion, there were no synergistic effects of sucrose and flaxseed oil on the conversion of SDG to EL in the rumen.