The seasonal variability of qualitative composition of the essential oil of G. hirsuta from six localities was investigated. Plants for this investigation were collected during April and July 1996. The distillation of essential oil was carried out according to Lickens-Nickerson method, using methylene chloride. Identification and quantification of the single components was carried out by GC and GC/MS. Seven compounds were identified from the essential oil: 1,8-cineole, octen-1-ol-acetate, 7-octen-4-ol, g-elemene, b-cubebene, benzen-methanol and viridiflorol. The dominant compound of essential oil of plants collected in April, in flowering stage, was 1,8-cineole, while in the oil of plants collected in July, during fruiting period, the main component was viridiflorol.