The essential oil from fresh leaves of Rosmarinus officinalis L. from Rio de Janeiro, Brazil, was isolated by hydrodistillation and analyzed through a combination of GC and GC/MS. Compounds representing 98.3% of the oil were identified. Forty-five constituents were identified according to their chromatographic retention indices and mass spectra. The major constituents of the oil were camphor (26.0%), 1,8-cineole (22.1%), myrcene (12.4%) and Î±-pinene (11.5%).