Our objective was to evaluate the effects of partial replacement of corn and alfalfa silage with tall fescue hay on total-tract NDF digestibility and lactation performance in dairy cows. Twenty-four primi- (75 ± 35 DIM) and 40 multi-parous (68 ± 19 DIM) Holstein cows were blocked by parity and randomly assigned to 1 of 4 treatment groups in a pen equipped with 32 feeding gates to record intake by cow. Each gate was randomly assigned to 1 treatment group, thus each cow had access to all 8 gates within the respective treatment and cow was the experimental unit. Treatments were formulated to partially replace corn silage (CS) and alfalfa silage (AS) with tall fescue hay (TF) as follows (DM basis): 67% CS and 33%AS (control), 60%TF and 40%AS (60TF40AS), 60%TF and 40%CS (60TF40CS), and 33%TF and 67%CS (33TF67CS). The experiment was a 7-week continuous lactation trial with a 2-week covariate period. Data were analyzed using the MIXED procedure of SAS. The model included parity, treatment, week, and relevant interactions as fixed effects and cow within treatment as a random effect. Dry matter intake and milk production did not differ, and averaged 23.5 and 41.4 kg/d, respectively. Fat concentration, protein yield and concentration, and SCC did not differ and averaged 4.00%, 1.28 kg/d, 3.15%, and 92.3, respectively among all treatments. Fat yield was greater (P < 0.01) for the control (1.65 kg/d), 60TF40AS (1.66 kg/d), and 33TF67CS (1.66kg/d) treatments compared with the 60TF40CS treatment (1.50 kg/d). Total-tract dry matter digestibility and total-tract organic matter digestibility did not differ, and averaged 67.9% and 70.0%, respectively. Total-tract NDF digestibility was lowest (P < 0.01) for control (40.8%), and greater (P < 0.01) for 60TF40CS (51.2%) than 60TF40AS (45.9%). 33TF67CS (46.7%) had similar total-tract NDF digestibility to the latter 2 treatments. Inclusion of highly digestible tall fescue grass hay has the potential to replace corn silage and alfalfa silage without influencing DMI and production.