Temperature data from oil wells, thermal springs and recent water wells have been compiled and used to construct a temperature gradient map for the northeastern part of the Iberian Peninsula. This map shows a gentle increase in thermal gradient from north to south and west to east with individual areas displaying both cold- and warm-temperature data. A very cold area near the Ebro Mouth, and a nearby anomalously warm area offshore are the most important features of the gradient map. These data are interpreted in terms of normal (30-35 mK m-1) geothermal gradient with conspicuous anomalies caused by groundwater circulation. This interpretation differs from previously published models of the thermal regime in northeastern Spain.