The pH, exchange and potential acidity were determined in soil samples taken at depths of 0-30 cm and 30-60 cm, under Pinus elliottii(19, 14 and 19 years old), Pinus patula (19 years old), Pinus taeda (19 years old) and under native "cerrado" vegetation at an adjacent área. The samples were collected in a Dark-red Latossol in Assis City, São Paulo State, Brazil. The effects of Pinus cover were an increase in soil acidity (pH, exchange and potential acidity). No differences were found among soil under Pinus stands, neither of different ages nor of different species.