Cassiaindoline is a new dimeric indole alkaloid isolated from Cassia alata L. leaves whose structure was elucidated through spectroscopic analyses. It exhibited analgesic activity at a dosage of 125.0 mg/kg mouse and decreased the number of writhings induced by acetic acid by 49.4%. It also showed a 57.1% anti-inflammatory activity at a dosage of 75 mg/kg mouse.