PROJECT SUMMARY/ABSTRACT Hypertension is the leading risk factor for chronic kidney disease (CKD). A recently published 30-year prospective cohort study revealed that the annual rate of decline in estimated glomerular filtration rate (eGFR) is exacerbated in adults with hypertension. Moreover, if albumin is present in the urine (i.e., albumuria), the annual reductions in eGFR are further exacerbated in adults with hypertension. Angiotensin converting enzyme inhibitors (ACEi) and angiotensin II type 1 receptor blockers (ARBs) are recommended to treat hypertension and for their ability to reduce albuminuria. However, ~54% of adults with hypertension with the highest classification of albuminuria are not currently undergoing treatment with ACEi/ARBs. Thus, there is tremendous opportunity to better develop non-pharmacological approaches that are effective at lowering blood pressure and reducing albuminuria. Unfortunately, however, exercise may not be ideal because only ~45% of patients with hypertension adhere to recommendations for physical activity and some individuals may be unwilling or have limitations where exercise is less feasible. There has been an uptick in research investigating the vast health benefits of heat therapy. Heat therapy refers to the use of frequent episodic increases in core temperature induced by exposures to hot environments, such as sauna bathing or hot water immersion, that ultimately induces beneficial health adaptations. In healthy adults, short-term heat therapy has been shown to reduce the incidence of albuminuria. However, a critical knowledge gap remains if heat therapy provides beneficial adaptations for the kidneys in adults with hypertension, including reducing albuminuria which would lower the risk for CKD. The current study aims investigate whether heat therapy is effective at lowering blood pressure and albuminuria in adults with hypertension. We will compare if 30 sessions of passive heat therapy using hot water immersion over 8-10 weeks reduces albuminuria in adults with untreated Elevated or Stage 1 Hypertension to a greater extent than 30 sessions of exercise training over the same time period. Additionally, we will determine whether 30 sessions of passive heat therapy reduces urinary NGAL to a greater extent than exercise training in adults with untreated Elevated or Stage 1 Hypertension. Demonstrating that heat therapy can be used as a novel treatment for Elevated and Stage 1 Hypertension is timely and important as there is a clear need for alternatives to exercise training and pharmacological approaches.