Abstract: The impurities in anaethetic ether were investigated by gas chromatographic-mass spectrometric method. GDX-502, a cross linked polystyrene beads was used as the column packing material. Thirteen impurities were discovered in anaesthetic ether, synthesized by ethanol-sulfuric acid method. Ten of them were identified. They are ethylene, propylene, isobutane, cyclobutane, three isomeric butenes, methyl ethyl ether, ethyl isopropyl ether, and ethyl acetate.