ABSTRACTThe fluctuations of the Rio del Plomo glaciers have been studied during the period 1909 to 1983 through the use of topographic maps, published data, aerial photographs taken in 1955, 1963 and 1974, and topographic measurements taken in April 1983, of the tongue of Glaciar Oriental del Juncal. There has been a general and important glacial recession between 1909 and 1974; two glacial tongues have repeatedly experienced sudden advances and are therefore considered to be surging glaciers.