Objectives were to evaluate behavior monitors to assess behaviors and ear temperature during an induced heat stress study using electric heat blankets (EHB). Eartags (Cow Manager SensOor, Agis Automatisering, Netherlands) were placed in left ears of trial cows (n = 8) before trial barn entry (P0). Cows were moved into individual stalls (curtain sided barn with radiant heaters). Cows acclimated to trial barn for 1 week (P1). Cows were then fitted with an EHB (Thermotex Therapy Systems Ltd. Calgary, AB, Canada) that was on for 1 week (P2). Data was summarized for the last 4 d of P 0 −2 (3 d acclimation). Following EHB removal, cows returned to their respective barn and monitored for 7 d (P 4 = 1–3 d post trial and P5 = 4–7 d). Surface ear temperatures (T) and acceleromenter movements were recorded and transcribed through proprietary algorithm into 5 behaviors (hourly or daily %): ruminating (R); eating (E); Not active or moving (NA); active (A); and very active. Twenty-four hr. continuous time lapse video was taken on cows during trial barn time. Freestall barn T before moving was −1–10⁰C, with ear T 1.6–20°C, reflecting changes due to daily and diurnal temperatures differences. Upon entry into trial barn (15–21+ °C), ear T immediately increased to 29–32°C, indicating increased blood flow and potential heat dissipation. Ear T remained between 29 and 35°C during trial barn period (w/out and with EHB). Daily average behavioral (DAB) % (SEM) for P0 were: R 40% (1.1); E 28% (1.45); NA 25% (1.02); A 4% (0.34); VA 3% (0.44). DAB % for P1 (slightly warmer trial barn acclimation) were: R 49%; E 17%; NA 24%; 5%: 5%. (E decreased 36% (P < 0.01) and R increased 23% (P < 0.05) compared with P0. Video showed decreased eating times and altered meal patterns but panting transcribed as a rumination movement. DAB% for P2 (EHB) were: R 63%; E 10%; NA 19%; 6%: 3%. (41 and 17% decrease in E and NA; 29% increase in R (panting) compared with P1 (P < 0.05). DAB for P 3–4 (return to barns) were: R 39,44; E 22,25; NA 31,24; A 3,3; and VA 4,3 (normal behaviors within 1–7d). EHB was successful and monitors can be an excellent tool to quantify behavioral changes in early and severe heat stress.