Our objective was to determine the effects of feeding hydroponically grown barley sprouts (HydroGreen Inc., Renner, SD) to dairy heifers on growth and rumen fermentation. A 12-wk randomized complete block design study was conducted using 20 Holstein and 4 Brown Swiss heifers [215.1 ± 25 d of age; body weight (BW) 229.7 ± 39 kg]. Treatments were (1) control (CON) diet which was a total mixed ration (TMR) with grass hay, corn silage, and ground corn and soybean meal as major concentrate ingredients; and (2) a TMR with 14% (DM basis) hydroponic barley sprouts (HYD) replacing a portion of the concentrate mix. Diets were fed for ad libitum intakes and formulated to be isonitrogenous and isocaloric (DM basis), although the CON was 66% DM and HYD was 44% DM. Intakes were measured using the Calan gates. Frame sizes, BW, and body condition scores (BCS) were measured on 2 d during wk 0, 2, 4, 6, 8, 10, and 12. Rumen fluid was collected 4 h post feeding via esophogeal tube every 4 wk. Data were analyzed in MIXED procedures of SAS 9.4 with repeated measures. Heifer DMI was greater (P < 0.01) for HYD (7.5, and 8.0 kg/d for CON and HYD, respectively; SEM = 0.42). Heifer ADG tended (P = 0.07) to be greater for the CON treatment (1.2, and 1.0 kg/d; SEM = 0.06). Body weight (289.7, and 282.4 kg; SEM = 2.02) and gain: feed (0.16, and 0.13; SEM = 0.01) were greater (P < 0.01) for the CON treatment. Withers height (121.7 and 121.9 cm; SEM = 0.54) and hip width (37.3 and 37.1 cm; SEM = 0.57) and BCS (3.11, and 3.10; SEM = 0.02) were similar (P > 0.05), but heart girth was greater (P < 0.01) for the CON heifers (146.0 cm, and 145.0 cm; SEM = 0.62). Rumen ammonia-N (21.0, and 24.5 mg/dL; SEM = 2.15), pH (6.75, and 6.70; SEM = 0.06), total volatile fatty acids (95.0, and 98.0 mM; SEM = 2.32) and acetate to propionate ratio (3.4, and 3.3; SEM = 0.13) were similar. Results indicated that replacing ground corn and some soybean meal with hydroponic fresh barley sprouts maintained rumen fermentation and heifer body frame growth with slightly decreased gain:feed. The decreased gain:feed was most likely because of the overall high moisture content in the HYD TMR.