The chemical composition of the essential oil of leaves of Eucalyptus procera Dehnh., cultivated in central Iran, was obtained by hydrodistillation and analysed by GC-MS. Forty-five constituents representing 99.6% of the total oil were identified. The main constituents of the oil were found to be 1,8-cineole (35.9%), α-pinene (25.6%) and viridiflorol (7.7%). Other representative compounds were identified as α-terpineol (3.6%), aromadendrene (3.5%) and trans-pinocarveol (3.0%).