Informal caregivers of stroke survivors experience elevated chronic stress and are at risk of developing depressive symptoms. The cumulative effects of chronic stress can increase allostatic load and dysregulate biological processes, thus increasing risk of stress-related disease. Stress-induced alterations in the pattern of cortisol secretion vary with respect to stressor onset, intensity, and chronicity. Little is known about the psychoendocrine response to stress in female caregivers of stroke survivors. The purpose of this study was to examine perceived stress, caregiver burden, and the association between caregiver depressive symptoms and diurnal cortisol in 45 females caring for a significant other who experienced a stroke within the past year. Women completed the Center for Epidemiologic Studies Depression Scale (CES-D) and collected saliva for cortisol upon awakening, 30 min postawakening, noon, and bedtime for 2 consecutive days. Results revealed that women had high levels of perceived stress and caregiver burden. In women with CES-D scores ≥ 16, salivary cortisol levels were significantly lower across the day relative to women with CES-D scores < 16. This difference persisted after adjusting for age, number of caregiving hours per week, perceived social support, and quality of sleep. Younger age was associated with more depressive symptoms as well as lower levels of cortisol at awakening and 30 min postawakening. Results demonstrate that the burden of caregiving increases risk of depressive symptoms and hypocortisolism across the day. Hypocortisolism may contribute to increased risk of depressive symptoms as a result of the loss of glucocorticoid attenuation of stress-induced inflammation.