Activation of the hypothalamic-pituitary-adrenal (HPA) axis is the defining feature of the stress response. Under the influence of both internal and external stressors, activation of the HPA axis causes increased synthesis of corticotropin-releasing hormone (CRH) in the hypothalamus. The objective this study was to determine an appropriate exogenous dose of bovine corticotropin-releasing hormone (bCRH) to stimulate the physiological effects of the HPA axis in steers as a method to test the sensitivity of the pituitary and adrenal gland. 14-month old Holstein-Friesian steers were either given saline (control) or bCRH (0.1, 0.3, 1.0 or 1.5 ìg/kg BW). Serial blood samples were collected at -15, 0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, and 180 min relative to time 0. Following administration of 0.1 ìg of bCRH/kg BW, the peak ACTH response was not significantly different from pretreatment baseline concentrations. Administration of 0.3, 1.0, and 1.5 ìg of bCRH/kg BW increased peak ACTH above pretreatment concentrations. Peak cortisol responses to all bCRH treatments were greater than those to pretreatment concentrations. In conclusion, bCRH challenge may be a useful method for testing the sensitivity of the hypothalamic-pituitary-adrenal axis in steers subjected to stressful husbandry conditions, and a minimum dose of 0.3 ìg of bCRH/kg BW is required to stimulate physiological effects of stressor hormones.