Piper umbellatum is a plant currently utilized in traditional medicine as a sedative. Administered to rats by intraperitoneal injection, an aqueous extract of this plant brings about an ataxia with a decrease in the animal's watchfulness which lasts about 48 hours. Are also concomitant to this decrease in watchfulness, a fall of the rectal temperature, a decrease of spontaneous motor activity as well as an increase of analgesic activity.