Brown Trout (Salmo trutta) response to warming stream temperatures has become an important consideration for fishery managers. To evaluate Brown Trout response to warm stream temperatures we tracked 12 adults (29-50 cm) implanted with temperature-sensitive radio tags (ATS #F1150) from July 1 to August 19 on the North Branch Au Sable River (Michigan). We were particularly interested in determining if fish would actively seek thermal refuge. Tracking occurred on 34 dates, multiple days a week and up to four relocations per day. Every 15 minutes water temperature and light were recorded at multiple locations within the study reach and at one “air” location using Onset MX2201 and MX2202 loggers. Water temperature was also recorded adjacent to relocated fish. Additional environmental data included water depth at one fixed site and barometric pressure. Out of 482 relocations, fish were found at their homesites 87% of the time. Only two fish had internal temperatures cooler (4.3% of relocations, 21 observations) than ambient stream temperatures. One fish (17 observations) occupied a homesite apparently setting over a groundwater discharge. A second fish initially occupied a cool water homesite (4 observations) but abandoned the site. When stream temperatures exceeded 20˚C (58.8% of relocations, 284 observations) or 25˚C (12.6% of relocations, 61 observations), except as noted above, there were no differences between body and stream temperatures. When Brown Trout left homesites at stream temperatures >21˚C (24 observation) or >25˚C (5 observations), body temperature remained similar to ambient. Most movement occurred during low-light conditions and increased stream depth regardless of temperature. Overall, Brown Trout exhibited limited use of thermal refugia and were not observed actively seeking refuge during warmer stream temperatures (23-26˚C). Limited use of thermal refugia may reflect weak thermal cues due to diffuse groundwater inputs, homesite fidelity, or adaptations to intermittent thermal stress.