The invention provides a physiological fluid temperature control apparatus with a conduit through which physiological fluid flows in use. The conduit is a tube, transparent to electroluminescent radiation incident upon it. Electroluminescent radiation sources are positioned such that the radiation they produce in use passes into the tube. The radiation is selected to have a wavelength strongly absorbed by physiological fluid, which leads to heating of the fluid. The apparatus may have temperature and flow sensors, as well as photosensors, to record information about the fluid in the conduit, and this information may be used by a controller configured to adjust power supplied to the radiation sources in order to maintain the temperature of the fluid within a predetermined range.
