In 1991, in order to assess changes in soil acidity, we resampled the mineral soil from 95 plots in beech forests distributed throughout northeastern France, ca. 20 years after a first sampling in 1970–1973. Changes between the two sampling dates were more conspicuous for acidic soils than for mesotrophic or calcareous soils. We observed a significant decrease in base saturation, exchangeable calcium, magnesium, and potassium in the whole profile of the acidic soils. Median cation losses calculated for these soils down to a depth of 80 cm were 18.7 kg ha⁻¹ yr⁻¹ for calcium, 2.7 kg ha⁻¹ yr⁻¹ for magnesium, and 2.4 kg ha⁻¹ yr⁻¹ for potassium. This loss was not reflected by changes in soil pH (measured in water extracts). The intensity of the cation losses and the analysis of the pollution climate over the last 20 years suggest that atmospheric deposition could have contributed to the observed changes.