This study examined the artefact induced in temperature measurements made withthermocouples and Luxtron fluoroptic probes in the presence of infraredradiation. Localized heating was created using a continuous-wave, 810 nm diodelaser system emitting 2.0 W from a cylindrical diffusing optical fibre, inair, water and an agar-albumin phantom. The temperature was measured every1.0 s for 10 to 150 s, with both a thermocouple and a Luxtron fluoroptic probeat distances of 2, 3, 4, 5, 6 and 7 mm from the cylindrical diffusing tip. Inall cases, the fluoroptic probe recorded a higher temperature than thethermocouple during laser irradiation. The difference in measured temperaturesbetween the Luxtron probe and the thermocouple ranged from 1.6 °Cto 18.8 °C in air, from 0.3 °C to 10.2 °C inwater, and from 1.4 °C to 10.1 °C in phantom, dependingon the distance of the probe from the laser source. The results suggest thatin the presence of laser irradiation, self-heating of the Luxtron probeinduces a significant artefact in temperature measurements at distances lessthan 4 mm from the source fibre. As a result, fluoroptic probes may not besuitable for monitoring tissue temperature for treatments when laserirradiation is present if sensors are located close to the fibre tip(<4 mm).