Free amino acids from the leaves of ten North American conifer species have been analysed by packed-column gas-liquid chromatography as their N(O,S)-heptafluorobutyryl isobutyl esters. The species examined were Balsam fir [Abies balsamea (L.) Mill], douglas fir [Pseudotsuga menzeisii(Mirb.) France], western hemlock [Tsuga heterophylla (Raf.) Sarg.], Rocky mountain juniper (Juniperus scopulorum Sarg.), western juniper (Juniperus occidentalis, Hook), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), ponderosa pine (Pinus ponderosa Laws.), black spruce [Picea mariana (Mill.) BSP], Colorado spruce (Picea pungens Engelm.), and white spruce [Picea glauca (Moench) (Voss)]. All the proteic amino acids and some biologically important non-proteic amino acids were readily assayed. Gas chromatography-mass spectrometry was used to confirm the identity of the proteic amino acids and the homogeneity of the corresponding peaks. Ten unidentified components were partially characterised by their mass spectra.