This study reports the free amino acid content of pollen grains obtained from old and fresh samples belonging to Pinus nigra subsp. nigra var. caramanica (Loudon) Rehder (black pine) (Pinaceae), Juglans regia L. (walnut) (Juglandaceae), Fraxinus angustifolia Vahl. (ash) (Oleaceae) and Betula pendula L. (birch) (Betulaceae) obtained with the technique of Liquid Chromatography-Mass Spectrometry (LC/MS). Pollen samples were obtained from flowers of the above mentioned taxa in different years. Twenty one amino acids were identified. No histidine was found in F. angustifolia collected 8 years ago. Total protein content of P. nigra subsp. nigra var. caramanica pollens (25.75%) was higher than the remaining taxa; F. angustifolia (13.67%), B. pendula (7.73%) and J. regia (7.55%).© Asian Network for Scientific Information.