Abstract The chemical composition of essential oils of Thymus arundanus Wilk, and its parents T. mastichina L. and T. baeticus Bois ex Lacaita were determined by GC, GC/MS and IR. The major components of T. mastichina oil were 1,8-cineole (42.6%), and linalool (32.8%), while those of T. baeticus were trans-sabinene hydrate (18.2%), borneol (13.7%) and verbenone (7.3%). The major oil components of T. arundanus were similar to those found in its parents: 1,8-cineole (46.4%), linalool (11.7%), trans-sabinene hydrate (3.3%), borneol (1.8%) and verbenone (1.1%), but its chemotype is closer to T. mastichina..