Summary The present paper establishes the relationship between certain components of oleoresin and the character of a tree as high producer (plus tree). The composition of the oleoresin (monoterpenes, sesquiterpenes, neutral diterpenes and resin acids) of Pinus pinaster in plus trees was studied by gaschromatography/mass spectrometry. The main components of the monoterpenes are α-pinene, β-pinene, limonene + β-phellandrene; of the sesquiterpenes β-caryophylene and longifolene; of neutral diterpenes isoabienol, abienol, isopimaral, pimaral, 11,13-labdien-8-ol and of resin acids levopimaric + palustric, neoabietic, abietic, isopimaric, pimaric, dehydroabietic, sandaracopimaric and 7,13,15 abietatrienoic acid. The components which enable us to distinguish between plus and control trees are myrcene and noracid 1 at a level of significance of 1%, and abienol and dehydroabietic acid at 5%. The composition of diterpenes permits a certain approach to distinguish between control and plus trees.