Groundwater depletion is one of the most pressing issues facing the dairy industry today. One strategy to improve the industry’s drought resilience involves feeding drought tolerant forage crops in place of traditional forage crops like alfalfa and corn silage. The objective of this study was to assess the productivity of lactating dairy cows fed diets with teff hay (Eragrostis tef) as the sole forage. Teff is a warm-season annual grass native to Ethiopia that is well adapted to drought conditions. Nine multiparous Holstein cows (185 ± 31 d in milk; mean ± SD) were randomly assigned to 1 of 3 diets in a 3 × 3 Latin square design with 18-d periods (14 d acclimation and 4 d sampling). Diets were either control (CON), where dietary forage consisted of a combination of corn silage, alfalfa hay, and prairie hay, or 1 of 2 teff diets (TEFF-A and TEFF-B), where teff hay (13.97 ± 0.32% CP, DM basis) was the sole forage. All 3 diets were formulated for similar dry matter (DM), crude protein (CP) and starch concentrations. CON and TEFF-A were matched for concentrations of neutral detergent fiber (NDF) from forage (18.23 ± 0.15% of DM), and TEFF-B included slightly less, providing 16.63% NDF from forage. Dry matter intake (DMI), milk and component production, body weight (BW), body condition score (BCS), as well as DM and NDF digestibility (DMD and NDFD) were monitored and assessed using mixed model analysis. Treatment had no effect (P = 0.76) on DMI (28.14 ± 0.75 kg/d). Similarly, treatment had no effect (P = 0.65) on milk production (40.68 ± 1.79 kg/d). Concentrations of milk fat (3.90 ± 0.16%) and lactose (4.68 ± 0.07%) were also unaffected by treatment (P > 0.10). TEFF-A and TEFF-B increased milk protein concentration (P < 0.001) compared with CON (3.07 vs. 3.16 ± 0.09%). Treatment had no effect on energy-corrected milk (ECM) yield (43.37 ± 1.26 kg/d), BW, or BCS change (all P > 0.10). Additionally, treatment had no effect (P = 0.47) on total-tract DM or NDF (P = 0.58) digestibility. Results from this study indicate that teff hay has potential to replace alfalfa and corn silage in the diets of lactating dairy cattle without loss of productivity.