Essential oil from Ramulus Cinnamomi (Cinnamomum cassia Presl) and Cortex Cinnamomi were obtained by steam distillation. The chemical components of the oil were examined and compared by means of gas chromatography-mass spectrometry. 54 of the separated constitutents were identified. 10 components of these were not observed in the oil from Ramulus Cinnamomi, and 16 components of these were not observed in the oil from Cortex Cinnamomi.