A microradiotelemeter was designed and developed to measure the in situ temperature of a tribocomponent (tapered roller bearing roller). Photolithography was used to pattern a flexible circuit board for the telemeter. The overall device size was minimized by the use of surface-mount technology (SMT) components. The completed circuit board was 5 mm by 9 mm by 1.5 mm high and weighed approximately 0.080 grams. The board was packaged in a brass body with a battery case and antenna. The complete package was installed into a bearing roller, with the thermally sensitive elements near the rib-roller contact. The telemeter was used with an RF spectrum analyzer to monitor the start-up temperature of a bearing roller for various applied loads and shaft speeds. Test results indicate that, under starved conditions, the temperature of the roller measured with the telemeter increased significantly faster than the temperature of the housing.