Imperialine is a steroidal alkaloid first isolated from the bulb of Fritillaria imperialis L. (Liliaceae). Bulbs of Fritillaria have been used in many Asian countries for a long time to treat pulmonary diseases, such as cough, expectoration, and asthma. Imperialine is one of the biologically active constituents in Fritillaria. It acts as a selective antagonist at muscarinic M2 receptors. It exerts antitussive, expectorant, and anti-inflammatory properties. In addition, imperialine demonstrated antineoplastic potential in vitro.