The chemical composition of the essential oils from leaves and young twigs ofxCupressocyparis leylandiiand cultivars ‘Naylor's Blue,’ ‘Castlewellan Gold’ have been elucidated by GC/MS and GC analysis. In all investigated oils, δ-3-carene (16.3%, 19.1%, 14.4%, respectively), α-pinene (10.0%, 12.2%, 24.7%), sabinene (15.7%, 20.7%, 9–0%) were revealed as the main components. InxC. leylandiiand ‘Castlewellan Gold’ limonene occurred in relatively large amounts (15.1%, 19–1%) in ‘Naylor's Blue’ only in small amounts (3.2%). The oil contents have been determined inxC. leylandii- 1.35% v/w, ‘Naylor's Blue’ - 2.7% v/w and ‘Castlewellan Gold’ - 2.1% v/w.