High resolution two-dimensional electrophoresis, with isoelectric focusing in the first dimension and electrophoresis in sodium dodecyl sulfate in thin acrylamide gels in the second dimension, has been applied to separate the proteins of single meristems (200-300 microns) from Sequoiadendron giganteum, Sequoia sempervirens, Pseudotsuga menziesii, Picea abies, Pinus pinaster, Eucalyptus gunnii and Populus nigra. The technique may prove an efficient tool for studying inter- and intraclonal differences in meristem cultures of forest species, especially when referring to cloning from meristems of selected trees in relation to the rejuvenation process.