GC-MS of ethyl acetate solutions and HS-SPME-GC-MS of mastic oil and mastic gum showed the presence of α-pinene and β-myrcene as main components of the mixture. In the GC-MS analysis of mastic oil 19 compounds were detected, while mastic gum allowed to detect only twelve compounds. Mastic gum showed the presence of compounds with a higher molecular weight. In HS-SPME analysis the amount of β-myrcene increased in comparison to the results obtained in the analyses performed in solution. The relative ratio between α-pinene and β-myrcene showed that SPME analysis induces a preferential detection for β-myrcene (α-pinene/β-myrcene in the mastic oil 16.18 in GC-MS analysis, and 5.06 in SPME analysis; α-pinene/β-myrcene in mastic gum 10.64 in GC-MS analysis, and 2.25 in SPME analysis). These results can be explained considering a different absorption selectivity of these compounds on the SPME fiber.