Notes: Summary Conventional heat-flow measurements in Chile carried out by other workers are summarized. Between latitudes 26 – 29° S heat flow is consistently low (〈42 mWm−2) excepting a site in the Andes slope (75.3 mWm−2). In Central Chile (33 °S) near Santiago, a value in the Andes (60.7 mWm−2) is lower than the value in the Santiago basin (78.7 mWm−2). Heat flow through the sea bottom around the Chile Ridge (about 44 – 48° S; 75 – 80° W) ranges between 25 and 414 mWm−2; heat-flow estimates based upon the location in depth of the phase of gas hydrates have also been carried out in this area. In Tierra del Fuego the only heat-flow value is 96.3 mWm−2. The present heat-flow studies in Chile do not allow any conclusions to be drawn on the general heat-flow distribution and its description within the frame of new global tectonics. Only some preliminary model results comparing heat-flow measurements in the area of the Chile Ridge to thermal effects produced by a ridge-trench collision may presently be partially adopted. A general discussion regarding the results from global seismic tomography, maximum depth of seismic coupling and thermal processes in Chile is also presented. The silica geotemperature in the Santiago basin resulting from 257 groundwater analyses is 77.4±10.4 °C; the equivalent heat flow is 92.5±16.6 mWm−2 which is in agreement with the conventional heat-flow value in this area. Geochemical thermometry indicates fluid temperature at depth higher than 200 °C in some of the 33 hot-spring areas evaluated using SiO2, Na-K-Ca and Na-Li geothermometers. The evalutation of fluid rock equilibrium and CO2 - fugacities by means of relative Na, K, Mg and Ca contents of thermal waters indicates that only in El Tatio and Puchuldiza in Northern Chile have fluids attained partial equilibrium with both K-Na and K-Mg mineral systems. Other geothermal areas in the north, and many hot springs in Central Chile, correspond to immature waters which are generally unsuitable for the evaluation of K/Na and K/Mg equilibrium temperatures. In Central Chile the evaluation of some hot-spring waters in partial equilibrium condition indicate deep temperatures between 80 °C and 245 °C. In the area of El Tatio the combined heat flow (conductive and convective) yields a value of 1465 mWm−2 with fluid circulating within 1 km of an underlying magmatic intrusion at 5 – 7 km depth. The water catchment area may be situated 20 km to the east of the geothermal area, with the underground fluid moving at a rate of about 1.3 kmy−1 Temperature logs in wells for oil prospection show that temperatures are affected by drilling disturbances. Some preliminary BHT estimates of gradients yield between 26.3°C km−1 and 72.4 °C km−1. Thermal conductivity and diffusivity data from these wells are also shown.