Based on hydrographic data collected since 1955, Mediterranean outflow waters present in the eastern North Atlantic show a density compensated increase in both temperature and salinity. With an increase in temperature of 0.101 ± 0.024°C/decade and an increase in salinity of 0.0283 ± 0.0067 psu/decade in the Mediterranean outflow waters, the heat content gain from 1955 to 1993 is calculated to be 2.02 ± 0.31 × 106 J/m3, which surpasses the average gain in heat content of the North Atlantic basin over the latter half of the 20th century. This suggests that the Mediterranean outflow waters are an important contributor to climatological changes at intermediate depths within the mid-latitude North Atlantic. Copyright 2004 by the American Geophysical Union.